Opinions - Cannabis and Driving - as bad as it's thought?

[FuBai]

It is a debate that has already occurred on this forum, but in more general terms, referring to all drugs rather than specifically Cannabis. The general conclusion was that driving whilst high was not acceptable. I would quite like to re-examine this position in relation to cannabis.

The fact is that the UK government has investigated the extent to which cannabis impairs your ability to drive and, remarkably, they noticed little detectable difference between the same person whilst sober and then whilst high. In fact most studies in this area show that driving after one joint of cannabis (an admittedly vague dosage amount) is no more dangerous than driving whilst not. There is even a video which can be found here in which a regular cannabis smoker is given a driving course to drive around, including following other traffic whilst sober and then whilst stoned. The report concludes that there was no difference between the two and suggests that the latter might actually have been the better.

Another interesting article can be found here, put on the BBC website in 2000. This is the synopsis of the government report I mentioned earlier and whilst the article does claim that some difficulties may arise, this only happens after a comparatively high dose. The report says that driving under the influence of cannabis "reaction times to motorway hazards were not significantly affected" that "the volunteers drove more slowly, trying to compensate for intoxication by being more cautious" and that "alcohol and tiredness have a more adverse effect on driving ability". This information also tallies with similar research from the US, the Netherlands and Austria. Another study that has been posted on this forum can be found here, and more information can be found here

Some even make an increasingly feasible (although still somewhat dubious) case that they drive better under the influence of Cannabis. However, none of the above should be treated as a licence to "Dope n' Drive", but it should help us to better understand the real risks of cannabis and auto mobile accidents and give proponents of legalisation a rather good foil to the American insistence that the legalisation of Cannabis would lead to more road accidents.

Reputation Comments on this post:

Nice thread!

[Paracelsus]

The need for compensating for intoxication by being more cautious and driving slowly is a clear sign that cannabis does impair driving ability. I doubt that the average crazed teenager would be responsible enough to drive more slowly & carefully after smoking.

An interesting way to determine the real impact would be to compare numbers of marijuana-related accidents with numbers of alcohol-related accidents and then calculate an accident probability index by dividing numbers of accidents to the numbers of marijuana or alcohol users, respectively.

[FuBai]

Originally Posted by Paracelsus

The need for compensating for intoxication by being more cautious and driving slowly is a clear sign that cannabis does impair driving ability. I doubt that the average crazed teenager would be responsible enough to drive more slowly & carefully after smoking.

An interesting way to determine the real impact would be to compare numbers of marijuana-related accidents with numbers of alcohol-related accidents and then calculate an accident probability index by dividing numbers of accidents to the numbers of marijuana or alcohol users, respectively.

The fact is that, whilst users felt the need to drive more carefully and cautiously, driving instructors could notice no difference between the sober and intoxicated laps. I think that a good argument could be made saying that Cannabis intoxication heightens some senses and therefore may well make the user more paranoid about their driving when in reality there is little to no impairment. These are, of course, opposing theories that are not proven, but I am inclined to believe that, even if you were correct in that assumption, the fact that it causes people to be more cautious and careful when driving overrules that possible impairment. The fact is that when we look at these sort of things we are studying them for the legislative ramifications they may have, and for this purpose we need objective analysis rather than subjective ones; thus rather than asking the drivers how they felt we should be looking almost entirely at how they performed, as this is the measure of whether Cannabis and Driving can be relativley safely mixed whilst posing no increased danger to other road users. How the driver feels whilst driving obviously correlates directly with this, but in this case performance is not noticeably reduced.

[Bajeda]

There is a review of the literature on cannabis and driving that picks up where the other study you linked to left off (post 1994 that is).


Cannabis and Driving: A Review of the Literature and Commentary


Conclusion

This report has summarised available research on cannabis and driving. The report has included the main review documents for research published before 1994 (e.g., Hall et al., 1994; Robbe, 1994) as well as primary sources for research published from 1994 using keyword searches of relevant databases. This synthesis of research was directed to identify key research objectives to develop a rational transport policy for cannabis and driving.

It is apparent that cannabis is the most common 'illicit' drug. Indeed, there is some evidence to indicate an increasing trend in its availability and use in the general population. Thus, in terms of drug use and traffic safety, this would suggest that cannabis represents the major drug type to be addressed by transport safety policy.

However, there is not sufficient evidence indicating the percentage of drivers that operate a vehicle after consuming cannabis, particularly during the time period of any intoxicating effect. As a result, there is no precise estimate of the percentage of drivers exposed to cannabis as an accident risk factor. Indeed, it is problematic to estimate the extent of exposure independent of other risk factors associated with cannabis use such as alcohol. Moreover, the demographic group most frequently using cannabis already has the greatest a priori accident risk due to driving inexperience and factors associated with youth relating to risk taking, delinquency and motivation. These demographic and psychosocial variables may relate to both drug use and accident risk, thereby presenting an artificial relationship between use of drugs and accident involvement.

The recent developments and discoveries in pharmacology such as cannabinoid receptors and endogenous ligands are important and exciting. These and the increased understanding of the mechanism of action of cannabis will mean that new or improved methods of detection are likely. Most promising to date in terms of reliability, detection of recent consumption and practical application are methods for determining presence of metabolites in saliva and sweat. These developments and ongoing research also have implications for therapeutic drug development. New compounds based on cannabinoids will need careful evaluation to confirm their lack of psychoactive and psychomotor effects.

Evidence of impairment from the consumption of cannabis has been reported by studies using laboratory tests, driving simulators and on-road observation. The laboratory tests generally indicate acute impairment of memory, attention and psychomotor control. Both simulation and road trials generally find that driving behaviour shortly after consumption of larger doses of cannabis results in (i) a more cautious driving style; (ii) increased variability in lane position (and headway); and (iii) longer decision times. Whereas these results indicate a 'change' from normal conditions, they do not necessarily reflect 'impairment' in terms of performance effectiveness since few studies report increased accident risk. However, the results do suggest 'impairment' in terms of performance efficiency given that the increased compensatory effort resulting from cannabis use limits the available resources to cope with any additional, unexpected or high demand, events.

In conclusion, cannabis impairs driving behaviour. However, this impairment is mediated in that subjects under cannabis treatment appear to perceive that they are indeed impaired. Where they can compensate, they do, for example, by not overtaking, by slowing down and by focusing their attention when they know a response will be required. However, such compensation is not possible where events are unexpected or where continuous attention is required. Effects of driving behaviour are present up to an hour after smoking but do not continue for extended periods.

"With respect to comparisons between alcohol and marijuana effects, these substances tend to differ in their effects. In contrast to the compensatory behaviour exhibited by subjects under cannabis treatment, subjects who have received alcohol tend to drive in a more risky manner. Both substances impair performance, however, the more cautious behaviour of subjects who have received cannabis decreases the impact of the drug on performance, where the opposite holds true for alcohol."
(Smiley, 1998, p. 19)

It is notable that the studies based on laboratory tests tend to indicate more effects of cannabis consumption than those using simulation and road observation methods. The higher incidence of effects under laboratory test conditions relative to the 'natural' conditions of simulation and road studies has been attributed to (i) reduced error variance from greater control of test conditions; (ii) higher task demand under novel test conditions; (iii) irrelevance or non-equivalence of laboratory test to component of driving; (iv) greater latitude for compensatory effort under 'natural' conditions; and (v) self-selection under 'natural' conditions not to be exposed to risk (e.g., not drive).

"It is exceedingly difficult to explain the disparity in results obtained by laboratory tests and in driving situations. Rather than try, it seems better for the moment to assume that both sets of results are valid for the particular circumstances under which they were obtained. It demonstrates, however, that performance decrements obtained under the artificial and non-life threatening conditions in the laboratory do not automatically predict similar decrements in driving situations that are closer to real-world driving." (emphasis added, Robbe, 1994, p. 66).

The greater propensity for cannabis effects under laboratory test conditions is somewhat paradoxical given that the laboratory tests have typically used smaller doses of cannabis than the simulation and road studies. It is also controversial since the limited number of studies and absence of demonstrable effects under natural driving conditions has impeded the development of transport policy regarding cannabis use. Whereas evidence of drug impairment under laboratory test conditions is not sufficient to provide an increase in accident risk, it does demonstrate cause for concern. This concern should then guide subsequent research under simulation and road conditons to investigate more valid evidence of impairment. Such efforts should be guided by relevant laboratory tests that relate to a model of driving, and use of a standard test methodology and reporting format for both simulation and road based research. This will provide a logical sequence of inquiry that can include both the replication of key findings, and the comparison of effects between a range of study designs.

Attempts to estimate the accident risk associated with cannabis use have relied on epidemiological evidence from accident involved drivers. Whereas this evidence has identified the presence of cannabis amongst accident involved drivers, accident risk can not be calculated given the absence of valid baseline data for cannabis detected in the non-involved population. Moreover, the presence of cannabis is often confounded by alcohol, as well as demographic and psychosocial risk factors associated with both drug and alcohol use. Current methodologies can only determine the presence of cannabinoids, but not evidence of impairment.

Thus, not only is it problematic to estimate the percentage of accident involvements associated with cannabis use alone, there is no evidence that impairment resulting from cannabis use causes accidents. Attempts to alleviate these problems by calculating risk of culpability for an accident (rather than the risk of having an accident) suggest that cannabis may actually reduce responsibility for accidents. It is evident that further epidemiological research is necessary. Such research must adopt a 'Grand Rapids' methodology of obtaining valid baseline data matched to positive cases, as well as including sufficient sample sizes and a valid operational definition of 'responsibility'. Such research may benefit from differentiating between accident types and accounting for relevant covariates including driver age and sex.

Much of the interest in cannabis as a potential accident risk factor is related to the concern about alcohol. Both alcohol and cannabis have an intoxicating effect that alters the psychological state of the individual. However, the mechanism of action and form of intoxication of these drugs are distinct. Alcohol may provide a useful metric to evaluate the effect of cannabis. Moreover, given the existence of a set legal limit for alcohol, research of the dose equivalence between alcohol and cannabis for performance relevant to accident risk may provide a method of determining a safety critical limit for cannabis. German research based on meta-analyses has concluded that 50% of performance is impaired at 11ng/ml THC, making this an equivalent level of intoxication to 0.08% BAC, although more recent and driving specific studies need to be compared with respect to effect size to confirm these suggested dose equivalences.

However, it is important not to use parallel reasoning between alcohol and cannabis to dictate the research agenda and transport policy for cannabis alone. Such reasoning is particularly inappropriate for medicinal applications of cannabis derivatives.

"There has developed an understandable but regrettable tendency to separate alcohol from other impairing agents and at the same time to enact tough drugs-driving legislation which remains firmly based on experience with alcohol. This is illogical, inappropriate and usually quite unenforceable. There is often pressure to define, for legal purposes, critical body fluid concentrations above which all would be impaired and below which no impairment would be demonstrable. At present, this is not possible. In addition to the considerably more complex pharmacokinetic and pharmacodynamic effects of most drugs compared with those of ethanol, there is also the proposition that therapeutic drugs, used for legitimate purposes, may improve the driving ability of certain patients despite their ability to impair performance normal individuals." (Starmer et al., 1988, p. 35-36)

One approach to deriving a legal limit for cannabis during driving has been to set the threshold to the level at which 50% of results show impairment. For alcohol, Berghaus showed a BAC of 0.073% corresponded to impairment on 50% of 923 performance measures examined. The corresponding threshold for THC was 11ng/ml. This is the closest estimate of dose equivalence to date, although there are recent, well-controlled studies which have not been included in such metaanalyses. A necessary research undertaking would be a thorough meta-analysis of results to date, using statistical measures of effect size related to dose.

An alternative is to specify a zero limit threshold, where any level of detected drug is prohibited. However, such an approach is premised on the philosophy that any drug which alters the state of the driver is inconsistent with the responsibility of the driver to operate the vehicle only when in an optimal state. This approach is associated with its own impracticalities of defining an 'optimal' state and deciding if reasons for impairment (i.e. deviation from the optimal state) other than drug use can be prosecuted (e.g., fatigue, poor driving skills, age related decline in capacity to drive etc.). Ultimately, the direction of transport policy will be decided by an assignment of relative priorities. On one hand, any drug that affects the alertness and capability of a driver to safely operate a vehicle must be precluded. On the other hand, there are other factors such as alcohol which have a stronger association with accidents.

"Of the many psychotropic drugs, licit and illicit, that are available and used by people who subsequently drive, cannabis may well be amongst the least harmful. Campaigns to discourage the use of cannabis by drivers are certainly warranted. But concentrating a campaign on cannabis alone may not be in proportion to the safety problem it causes" (Robbe, 1994, p. 177).

The main conclusion from this report is that there is insufficient evidence of the accident risk associated with cannabis. Future research directed to the formulation of transport policy is required to resolve many key issues that remain unresolved in relation to cannabis and driving. However, it must be recognised that these issues may not be readily resolved given the ethical, legal, and technical impediments of the research domain (Hall et al., 1994).

This call for additional research was set forth by Robbe (1994) at the conclusion of his oft cited treatise on cannabis and driving:

"This dissertation should not be considered as the final word. It should, however, remain for a while as a point of departure for subsequent studies that will ultimately complete the picture of cannabis effects on driving performance" (p. 177).

It is now imperative that funding is made available to facilitate further research. However, such research must also be supported by mechanisms to accommodate legal and ethical requirements in this area. "In the meantime, cannabis users should be urged not to drive while intoxicated by cannabis, and they should be particularly warned of the dangers of driving after combining both alcohol and cannabis" (Hall et al., 1994, p. 50).

Reputation Comments on this post:

Thanks for the contribution

[moda00]

Interesting.. It is a good point that the perceptions of the driver- which may be influenced by the drug- do NOT translate into differences by objective observation in studies. Swim's personal experience is that she does feel the need to be "more" careful, but this may be entirely perception. For example, whilst she is aware while stoned of double or triple checking before making a maneuver like pulling out onto a roadway or changing lanes, she may well do the same sober but doesn't think about the fact that she is doing it. As for speed, I think she does drive slower- not under the speed limit, but at or maybe +5 mph max while stoned, because she is aware that the legal implications of getting noticed/pulled over for something like speeding increase while using an illegal substance. When sober, she admittedly speeds more than she should, and is working on this, but she finds it easy to space out and become unaware of her speed-something she often tries to counteract by using cruise control. With marijuana, the stakes of getting pulled over are higher, and the perceived potential for impairment lead to a sense of increased need for vigilance and perfection while behind the wheel.

Another example, is that while stoned, she sometimes feels very aware of certain things- the way her body moves when walking, the way her mouth/lips are positioned, the movement of her hands. So while these things are completely natural and not likely much different while sober, one is simply more aware of them, and one's perception is altered and drawn to things which are otherwise overlooked..

[Dark_Man_Of_Peace]

SWIM drives more carefully while under the influence of an unmentionable herb. It' unmentionable cause SWIM forgot what it was. LOL

[chrisn]

Speeds feel faster to my pet dragon when high, 50mph easily feels like 60mph or more. This builds in an incentive to drive a bit slower.

[psyche]

Speed definately feels faster to SWIM and he doesn't drive as fast as when sober, but not below the limits either. He is scared sometimes because he falls so easily into hypnotic state that he isn't at all concentrated at road and finds himself in a whole different world when he wakes up to realize he is actually driving a car. But this just feels scary because he isn't used to it. This happens when he drives a silent road to his home, which is the same road he has been driving to school in the past years, so no wonder it is so familiar that he falls into a transe. Driving while stoned is very relaxing to a certain point of intoxication, but usually happens pretty automatically if you don't need to drive in a new or complex environment and you have some experience behind the wheel. SWIM was allowed to drive once in a while since he was thirteen, so by the time he went to driving school, he had some 3000 kilometers of experience on a road.

[skylined]

A drunk will blow right through a stop sign... a pothead will stop and wait for it to turn green I can drive fine stoned... I just do shit like miss turns, exits, burn my seats, drive slow, etc.

[FuBai]

Originally Posted by skylined

A drunk will blow right through a stop sign... a pothead will stop and wait for it to turn green I can drive fine stoned... I just do shit like miss turns, exits, burn my seats, drive slow, etc.

I'm sure that you, of course, have no personal experience in this area. You are referring to SWIM your loveable but misguided self-incriminating buddy whom you have seen doing these things.

[AntiAimer]

Whether alot of people can drive while high or not, it's still wrong. Smurf knows he can, should he though, no.

But he also thinks people who smoke fags shouldn't be able to while driving either, but that's a double standard so it's perfectly fine.

[FuBai]

Originally Posted by AntiAimer

Whether alot of people can drive while high or not, it's still wrong...

We are not really talking about smoking WHILST driving, which carries all the concomitant risks of having one hand off the wheel and holding something else. What we are really talking about is smoking THEN driving. If this is what you meant then you need to explain why you think it is wrong. Your opinion is worthless unless backed up by sensible reasoning.

[Nature Boy]

DUI of cannabis will never be accepted although I can imagine many smokers would not be effected negatively at all. It comes down to experience and common sense, two things many young drivers do not have.

[FuBai]

Originally Posted by Nature Boy

It comes down to experience and common sense, two things many young drivers do not have.

It is equally reasonable to say that these are requirements for driving full stop. So yes, I can see your point in that young people have a higher prevelance of Cannabis use and also less road experience, however I would say that the argument that young people have less common sense and experience would be an argument to raise the legal drive age limit. Driving tests are meant to asses these things and once someone has passed their test (and I refer to the British Driving test, as I have no knowledge of how the Americans examine driving the the go-carts they call "automatics") then they are considered responsible enough to drive. I suppose what the over-arching point is that people without the ability to drive in a consistent and reasonable fashion should not be on the road, and if they are the fault lies in the testing system. I would agree with you that driving whilst stoned is unlikely to ever be widely accepted, but this is not the fault of the act itself, but rather the ignorance and prejudice that surrounds it.

[Micklemouse]

Originally Posted by FuBai

I would agree with you that driving whilst stoned is unlikely to ever be widely accepted, but this is not the fault of the act itself, but rather the ignorance and prejudice that surrounds it.

Would you use this argument to support driving whilst drunk or tripping?

The fact of the matter is that driving whilst stoned is not seen by many as a problem, when in fact it is. Not only is it a criminal offence, it is also irresponsible, & the same could be said of any psychoactive substance - can anyone guarantee that they are in full control of their reactions when under the influence of cannabis or that their reaction times are not impaired? Will a stoned driver's heart rate recover as quickly as a non-stoned driver after a near miss, or will they carry on driving with an increased heart rate, still pumped with adrenaline, further impairing their judgement & reactions? The fact that people may drive slower when stoned doesn't hold any water at all - speed limits are designed to provide a safe speed to drive in any given area; driving at a slower pace can be as dangerous as speeding in these areas.

From reading the literature the only real justification I can find is that cannabis users have more awareness that they are stoned than say a drinker has that they are drunk, & are better able to compensate for their intoxicated state

From the US Department of Transport study 1993

Subjects' ratings of driving quality and effort to accomplish the task were strikingly different from the driving instructor's ratings. Both groups rated their driving performance following placebo as somewhat better than 'normal'. Following the active drug, ratings were significantly lower (35%, p<.009) in the marijuana, but not (5%, ns) in the alcohol group. Perceived effort to accomplish the driving test was about the same in both groups following placebo. Following the active drug, a significant (p<.033) increase in perceived effort was reported by the marijuana, but not the alcohol group.

Thus, there is evidence that subjects in the marijuana group were not only aware of their intoxicated condition, but were also attempting to compensate for it. These seem to be important findings. They support both the common belief that drivers become overconfident after drinking alcohol and investigators' suspicions that they become more cautious and self- critical after consuming low doses of THC, as smoked marijuana.

(Note that "attempting to compensate" does not necessarily equate to "being able to compensate", as this study states:

The results of the studies corroborate those of previous driving simulator and closed-course tests by indicating that THC in inhaled doses up to 300 g/kg has significant, yet not dramatic, dose-related impairing effects on driving performance (cf. Smiley, 1986). Standard deviation of lateral position in the road-tracking test was the most sensitive measure for revealing THC's adverse effects. This is because road-tracking is primarily controlled by an automatic information processing system which operates outside of conscious control. The process is relatively impervious to environmental changes but highly vulnerable to internal factors that retard the flow of information through the system. THC and many other drugs are among these factors. When they interfere with the process that restricts road-tracking error, there is little the afflicted individual can do by way of compensation to restore the situation. Car-following and, to a greater extent, city driving performance depend more on controlled information processing and are therefore more accessible for compensatory mechanisms that reduce the decrements or abolish them entirely.

)

The study concludes that

Although THC's adverse effects on driving performance appeared relatively small in the tests employed in this program, one can still easily imagine situations where the influence of marijuana smoking might have a dangerous effect; i.e., emergency situations which put high demands on the driver's information processing capacity, prolonged monotonous driving, and after THC has been taken with other drugs, especially alcohol. Because these possibilities are real, the results of the present studies should not be considered as the final word. They should, however, serve as the point of departure for subsequent studies that will ultimately complete the picture of THC's effects on driving performance.

Something to bear in mind when looking at any study on this is that dose was carefully monitored. In real life strength of dose varies considerably. I doubt very much that there are many if any users of cannabis who know exactly how much THC is in their spliff, never mind their system, & this amount will blatantly vary.

Personally, I cannot believe this is even open to debate outside of the context of clinical study. Driving under the influence of any psychoactive substance is just plain wrong. End of story.

[FuBai]

Originally Posted by Micklemouse

Would you use this argument to support driving whilst drunk or tripping?

I would refer you to my original statement; and I quote:

Originally Posted by FuBai

However, none of the above should be treated as a licence to "Dope n' Drive", but it should help us to better understand the real risks of cannabis and auto mobile accidents and give proponents of legalisation a rather good foil to the American insistence that the legalisation of Cannabis would lead to more road accidents.

In response to the other information posted there may well be some truth in this, although US government backed research is not exactly famous for its lack of political bias. I would still revert to the statement I made in the orginal drugs and driving thread, that being that what a driver should be judged on is competency and competency alone. It does not matter if he's drunk, but it matters if this renders him incompetent to drive. Tests need to be devised and indeed are being devised to asses competence in isolation, because that is all that matters when you are at the wheel - purely and simply competence or else you start down the slippery slope of driving whilst objectionable. When we make laws concerning road safety we should have in mind the safety of other road users first and foremost, the property and possessions of others secondly, and then the safety of the individual behind the wheel. So, logically, we should ask ourselves what it is that actually affects these considerations - this is competence. Yes, other factors feed into competence, but these factors do not necessitate incompetence although they may influence it. The worst thing about these sort of laws is that they are grossly inaccurate and impersonal because it creates a single value for all, whether or not that value accurately represents incompetence for the individual in question. These forums abound with warnings that different people react differently to different drugs and this is precisely my point, if each individual is different then an assessment of intoxicated driving is NOT the fact of incompetence or even slight impairment, it is ONLY the fact of intoxication. It is precisely because intoxication does not necessitate impairment that it is unfair to punish people on these grounds. The absolutely brilliant thing about assessing competence is that it's a catch all - once you have a basic test for assessing competence it will catch out, indiscriminately, all those who are incompetent for whatever reason. Thus those who are irresponsibly driving whilst too tired or too old or whatever other factors which MAY render someone incompetent are caught equally, and this I can only see as being right and proper as they pose as great a risk to the aforementioned considerations. Once the sole value and assessment is competence then there is one simple law that fits everyone and is fair to individuals. The only problem is the development of accurate tests to asses competence, but I believe there are already quite a few people working towards this goal.

[Nature Boy]

I suppose it's almost like the gay couple adoption thing. Technically, it shouldn't be a problem but the adopted kid would have to endure the abuse of society and would be at an automatic level of vulnerability.

I don't so much think the legal age for driving should be increased, it just doesn't really make sense comparatively, this from a US perspective. Driving at 16, dying for your country at 18, cold beer at 21. Seems like the order is a bit screwed up.

[Nature Boy]

Although I agree with Micklemouse in that driving under the influence of any notable psychoactive substance is generally wrong, I can see some sticky arguments arising from such a statement. If driving under the influence is wrong, then so is driving whilst fatigued and so it should become a criminal offense. Traffic cops shining torches in your eyes seeing if you're trying to catch forty winks behind the wheel. Also, driving in old age would have to be seen as "wrong" seeing as older people naturally have slower reaction times thus there would have to be an age limit imposed on drivers. Either that or they would have to renew their licenses on a very regular basis having to pass scrutinous medical examinations. A law might have to be passed banning drivers from operating their vehicles whilst physically ill or being emotionally upset because again, you can't guarantee your reaction times whilst being distracted by something else.

It's sad that we still rely on human ability to operate motor vehicles. Automatic cars run on a computer grid should be the norm by now forever ending human error in traffic collisions. The technology is available and should be applied ASAP.

[Micklemouse]

To be honest, & maybe I'm getting more reactionary in my old age, I do actually think that accidents caused by fatigued drivers should indeed be harshly penalised, & that regular re-testing should indeed be mandatory, not just for the elderly. One has to be responsible for one's actions, especially when it comes to being in charge of a ton or more of metal travelling at speed - if one cannot guarantee that one's reactions or skills are not up to par, then the vehicle should not be started, whether through age, fatigue, influence of drugs (remember also that some prescribed medications require declaration to licensing authorities) or plain incompetence.

EDITORIAL - Bizarre Accident Shows Danger Of Elderly Drivers

BBC News | ENGLAND | Driver fatigue: A big killer

As for automated vehicles, there is a potential, but there still has to be a human element involved in case of system failure. This human element must still be able to respond quickly & appropriately to an emergency situation - if anything quicker, because automation will mean that the human will not necessarily be taking much notice of what is happening on the road. A comparison would be to airline pilots, who apart from takeoff & landing have little to do generally, but must still be fully competent, just in case...

[Micklemouse]

The inference that is ok to "Dope'n'Drive" is there all the same FuBai.

As I stated earlier, the studies fall down because in real life standardised doses of cannabis are not used. Many people drive well after a couple of units of alcohol, an alcoholic would drive terribly if he had not had a drink, a newcomer to alcohol would drive terribly if he had had a drink. These truths are the truths that come out of the studies, only applied to cannabis. The difference is that there are limits to the amount of alcohol it is deemed safe to drive under the influence of. This is easily worked out to due to the standardised dosing of alcohol. There is no standardised dosing when it comes to cannabis, making any argument that it may be 'safe' to drive under the influence in the real world inherently flawed, irrespective of any studies made. If cannabis were legal, then a safe limit for the general population may be possible to work out.

For a bit of balance, a real life study

Cannabis intoxication and fatal road crashes in France: population based case-control study

Spoiler follows:

What is already known on this topic Cannabis consumption, even in low doses, hampers certain faculties necessary for driving a vehicle
Epidemiological studies provide conclusions that are heterogeneous and not robust enough to prove that such consumption represents a crash risk factor of significant magnitude
What this study adds
The risk of responsibility for fatal road crashes while driving under the influence of cannabis has a significant dose effect that shows a causal relation between cannabis and crashes
Reliable estimates of the share of fatal crashes attributable to cannabis and alcohol enable comparison of the respective road safety issues

[FuBai]

Originally Posted by Micklemouse

The inference that is ok to "Dope'n'Drive" is there all the same FuBai.

Really, where did I say that? What I said was that research seems to indicate that after a certain amount of cannabis little impairment is noticeable. I posted this evidence not to create a justification for doping and driving, in fact I specifically said that it was helpful in re-examining the laws pertaining to this subject and to discredit the American insistence that the legalisation of cannabis would lead to more car accidents. I did not say that there is no such thing as too much cannabis - in fact I said, very specifically, that different drugs affect people in different ways and so the only fair test is competency. That is what I said, and nothing more - the above inference is specious in the extreme.

Originally Posted by Micklemouse

As I stated earlier, the studies fall down because in real life standardised doses of cannabis are not used.

1) At least one of the studies shown used no standardised dosing.

2) Under a system of legalisation it is perfectly possible to standardise dosing to a functional extent. All this advocates is a limit system, which I have stated is unfair and explained why in great detail.

Originally Posted by Micklemouse

Many people drive well after a couple of units of alcohol, an alcoholic would drive terribly if he had not had a drink, a newcomer to alcohol would drive terribly if he had had a drink. These truths are the truths that come out of the studies, only applied to cannabis. The difference is that there are limits to the amount of alcohol it is deemed safe to drive under the influence of. This is easily worked out to due to the standardised dosing of alcohol. There is no standardised dosing when it comes to cannabis, making any argument that it may be 'safe' to drive under the influence in the real world inherently flawed, irrespective of any studies made. If cannabis were legal, then a safe limit for the general population may be possible to work out.

I have already stated why a limit is grossly unfair, inaccurate and impersonal.

For a bit of balance, a real life study

Cannabis intoxication and fatal road crashes in France: population based case-control study

Spoiler follows:

Fascinating study, however not really useful. You can say that cannabis causes reckless driving, or equally those who are inclined to drive whilst intoxicated UNDER THE PRESENT STATE OF AFFAIRS are more likley to be reckless. This is a very easy position to justify as most people do not know or have not heard about these studies and so believe that driving under the influence of cannabis is equal to driving whilst drunk. Certainly this is the information put about by police officers and other officials who most likley believe it to be true themselves. Thus the sort of person who believes that driving whilst high is the same as driving whilst drunk but goes ahead and does it anyway is likley to be a more reckless person.

You seem to have somewhat ignored the final argument that I made, and I await your response on this, such as it will be.

[Bajeda]

In conclusion, cannabis impairs driving behaviour. However, this impairment is mediated in that subjects under cannabis treatment appear to perceive that they are indeed impaired. Where they can compensate, they do, for example, by not overtaking, by slowing down and by focusing their attention when they know a response will be required. However, such compensation is not possible where events are unexpected or where continuous attention is required. Effects of driving behaviour are present up to an hour after smoking but do not continue for extended periods.

"With respect to comparisons between alcohol and marijuana effects, these substances tend to differ in their effects. In contrast to the compensatory behaviour exhibited by subjects under cannabis treatment, subjects who have received alcohol tend to drive in a more risky manner. Both substances impair performance, however, the more cautious behaviour of subjects who have received cannabis decreases the impact of the drug on performance, where the opposite holds true for alcohol."
(Smiley, 1998, p. 19)

It is notable that the studies based on laboratory tests tend to indicate more effects of cannabis consumption than those using simulation and road observation methods. The higher incidence of effects under laboratory test conditions relative to the 'natural' conditions of simulation and road studies has been attributed to (i) reduced error variance from greater control of test conditions; (ii) higher task demand under novel test conditions; (iii) irrelevance or non-equivalence of laboratory test to component of driving; (iv) greater latitude for compensatory effort under 'natural' conditions; and (v) self-selection under 'natural' conditions not to be exposed to risk (e.g., not drive).

I think it would simply be best for one to wait until the cannabis high had worn off to a good enough extent that relatively safe driving is possible. If you feel noticeably high, just chill out for a bit longer and don't rush out the door, whats the hurry anyways? Swim sometimes tends to not feel like moving whilst high anyways, so why would he care to go and drive home while feeling high to the point where cognition is impaired, and if he has someplace to be then why did he get high in the first place? I think the problems of driving high could be readily avoided through self-evaluation of one's mental state, allowing time to sober up before driving, using public transportation instead of driving when one desires to get high but is not sure of when they need to leave, getting a ride from someone else, etc.

One's self-perception of impairment is important. With alcohol it is much easier to overestimate ones skill level, whereas with cannabis one will likely be more aware of the risks. One such risk is that one may misjudge the relative risk if they are in an area they drive in frequently or are used to driving high much of the time. As the meta-analysis mentions, "compensation is not possible where events are unexpected or where continuous attention is required." Cannabis still has a notable tendency to slow response time, which could end in disaster for even the most careful drivers should something unanticipated occur.

I think leaving an acceptable period of time between smoking and driving would be preferable to driving while intoxicated in any manner, but recognize that some people feel they don't have a problem driving high. Still, until further research can corroborate or contradict current suspicions about driving high, I think people should bit the (extremely tiny) bullet and leave some 'sober-up' time after smoking before driving off, in the interest of everyone else on the road. I'm sure people drive when they are excessively high, just as people drive while drunk, fatigued, emotionally off-center, etc. It can be difficult to do anything about some, given that except in extreme circumstances (such as where someone gets hurt) it is very hard to detect that someone is too fatigued to drive unless they are visibly so (which may only occur by the time its too late to avoid a wreck). Still, people should be responsible and not put others at risk.

[moda00]

Originally Posted by Bajeda

I think it would simply be best for one to wait until the cannabis high had worn off to a good enough extent that relatively safe driving is possible. If you feel noticeably high, just chill out for a bit longer and don't rush out the door, whats the hurry anyways? Swim sometimes tends to not feel like moving whilst high anyways, so why would he care to go and drive home while feeling high to the point where cognition is impaired, and if he has someplace to be then why did he get high in the first place? I think the problems of driving high could be readily avoided through self-evaluation of one's mental state, allowing time to sober up before driving, using public transportation instead of driving when one desires to get high but is not sure of when they need to leave, getting a ride from someone else, etc.

One's self-perception of impairment is important. With alcohol it is much easier to overestimate ones skill level, whereas with cannabis one will likely be more aware of the risks. One such risk is that one may misjudge the relative risk if they are in an area they drive in frequently or are used to driving high much of the time. As the meta-analysis mentions, "compensation is not possible where events are unexpected or where continuous attention is required." Cannabis still has a notable tendency to slow response time, which could end in disaster for even the most careful drivers should something unanticipated occur.

I think leaving an acceptable period of time between smoking and driving would be preferable to driving while intoxicated in any manner, but recognize that some people feel they don't have a problem driving high. Still, until further research can corroborate or contradict current suspicions about driving high, I think people should bit the (extremely tiny) bullet and leave some 'sober-up' time after smoking before driving off, in the interest of everyone else on the road. I'm sure people drive when they are excessively high, just as people drive while drunk, fatigued, emotionally off-center, etc. It can be difficult to do anything about some, given that except in extreme circumstances (such as where someone gets hurt) it is very hard to detect that someone is too fatigued to drive unless they are visibly so (which may only occur by the time its too late to avoid a wreck). Still, people should be responsible and not put others at risk.

I agree that if one feels "too high" of thinks they may be impaired, they should refrain from getting behind the wheel. However, your point that self-perception is of importance may or may not be true. Like you point out, with alcohol, studies show an "overconfidence" with regard to actual ability, and I'm sure many of us have observed that effect in practice- ie. individuals who state they "drive better drunk," or individuals who become obstinate and must be physically prevented from driving when too drunk to do so. With cannabis, it seems the opposite effects are prominent- ie. a user can feel impaired but their performance cannot be designated as such by professionals. I would be interested to know if this hypothesis is correct- that users know they are impaired and compensate, thereby decreasing the effects on performance, or if it is possible that users may be more aware of certain things, and may feel that they have to be more cautious, but in fact it could be entirely perception? For example, if one feels "too high" to drive but has to get somewhere, for example in an emergency, will their performance be affected? And if so, is this because their perception is such, or because of some objective effect of cannabis? I don't think that one's perception of impairment is always the best indicator of actual impairment, although you make a good point that if one feels impaired, they should err on the side of caution and choose not to get behind the wheel. That said, in this case, it seems clear that subjective perception does not always match objective observation, and it is not clear whether this is due to to a user making an actual effort to change their driving behavior, or if it is completely irrelevant. In addition, with other factors like tiredness or age impairment, it seems subjective perception of ability is not sufficient to be the gauge by which these things are decided. An individual who is perfectly competent one day could be completely impaired the next, with no substances involved whatsoever.

I also think it is a good point that while certain things may be statistically associated, it does not mean A causes B. B could cause A, or C could cause both A and B, or it could be completely unrelated. For example, social influences and perceptions may influence who is likely to drive under the influence, as may certain personality indicators. So, as pointed out, if the group with the highest use of cannabis happens to be the group with the least driving experience and/or most reckless driving behaviors, one cannot necessarily infer that cannabis directly caused these accidents. In addition, the study quoted that divided the groups by the "at fault" driver, and the "passively involved" driver, may not be accurate either. This is difficult to objectively determine, as most accidents combine a number of factors, including both drivers, passengers, weather, etc. Sometimes both are "at fault," sometimes neither, and this may not be the best way to evaluate the situation. Also, think about conditions like passengers in the car- distractions like cell phones, eating while driving etc. There are so many factors that must be accounted for. I would be interested in hearing further research on this, however, we must note that no study is perfect- note the differences between studies of simulated driving vs. actual driving environments, or the differences between self-reported perceptions of impairment, and others' ability to tell one is impaired. Also, there are ways to study "unexpected" events- I can't recall the source, but I remember being shown a video clip of a study relating to tired drivers, which measured both "normal" conditions- speed, lane placement, et. and also simulated an unexpected event- an object popping out into the road in front of them- I think it was a child's ball or something, or an animal. So there are definitely ways to measure both "normal" conditions, and unexpected ones, but we must remember that the funding of a study, the controls, the way it is conducted, etc. has a huge impact on the results, and that is why we often say statistics or studies can be made to say whatever one wants them to say- you have to take into account the motives of the study, the methods used, and use multiple trials and accurate procedures to determine accuracy of the results.

[AntiAimer]

The problem is, so many things alter the mind. From things we all injest daily to things we do, but it all comes back to the double standard society has set.

Illegal or not, people will do it and people will get away with it and some won't. Also people may not get away with it but will not get the same crime since alot of things are in that "double standard" category.

Like for example, someone who's been hyperventilating themselves and then crashes isn't going to get a DUI\DWI\DWD\DWImpaired or someone who took to much caffeine and then suffers the side-effects leading to a crash. Or even someone who smokes fags and also suffers the side-effects will NOT fall under DUI\DWI\DWD\DWImpaired.

They can make it against the law, but they also have to catch you breaking it. Prooveing you where\are under the influence and\or are impaired. Which the police are already on there way on finding ways to proove people are on drugs and impaired while driving.

[moda00]

Originally Posted by AntiAimer

The problem is, so many things alter the mind. From things we all injest daily to things we do, but it all comes back to the double standard society has set.

Illegal or not, people will do it and people will get away with it and some won't. Also people may not get away with it but will not get the same crime since alot of things are in that "double standard" category.

Like for example, someone who's been hyperventilating themselves and then crashes isn't going to get a DUI\DWI\DWD\DWImpaired or someone who took to much caffeine and then suffers the side-effects leading to a crash. Or even someone who smokes fags and also suffers the side-effects will NOT fall under DUI\DWI\DWD\DWImpaired.

They can make it against the law, but they also have to catch you breaking it. Prooveing you where\are under the influence and\or are impaired. Which the police are already on there way on finding ways to proove people are on drugs and impaired while driving.

You are right. And the interesting thing about that is, certain illegal drugs (especially and most notably cannabis, but others too) stay in your system so long that they could test someone and convict them for DUI when in reality the actual high/drug effects were not affecting the individual at the time of the incident. Whereas things like being emotionally off center, legal and socially accepted highs- caffeine, nicotine, etc., or distractions like cell phone use, music, etc. are either not prosecutable, or not provable in a legal sense.