Marijuana

"Prohibition has two effects: on one hand it raises supplier costs, disrupts market functioning and prevents open promotion of the product; on the other, it sacrifices the authorities’ ability to tax transactions and regulate operation of the market, product characteristics and promotional activity of suppliers. The cannabis prevalence rates presented in Figure 1 show clearly that prohibition has failed to prevent widespread use of the drug and leaves open the possibility that it might be easier to control the harmful use of cannabis by regulation of a legal market than to control illicit consumption under prohibition. The contrast between the general welcome for tobacco regulation (including bans on smoking in public places) and the deep suspicion of prohibition policy on cannabis is striking and suggests that a middle course of legalised but limited consumption may find a public consensus."

"Analysis of the demographic and social characteristics of a large sample of applicants seeking approval to use marijuana medically in California supports an interpretation of long term non problematic use by many who had first tried it as adolescents, and then either continued to use it or later resumed its use as adults. In general, they have used it at modest levels and in consistent patterns which anecdotally-often assisted their educational achievement, employment performance, and establishment of a more stable life-style. These data suggest that rather than acting as a gateway to other drugs, (which many had also tried), cannabis has been exerting a beneficial influence on most."

The DEA's Administrative Law Judge, Francis Young concluded: "In strict medical terms marijuana is far safer than many foods we commonly consume. For example, eating 10 raw potatoes can result in a toxic response. By comparison, it is physically impossible to eat enough marijuana to induce death. Marijuana in its natural form is one of the safest therapeutically active substances known to man. By any measure of rational analysis marijuana can be safely used within the supervised routine of medical care.:

Since 1969, government-appointed commissions in the United States, Canada, England, Australia, and the Netherlands concluded, after reviewing the scientific evidence, that marijuana's dangers had previously been greatly exaggerated, and urged lawmakers to drastically reduce or eliminate penalties for marijuana possession.

In May of 1998, the Canadian Centre on Substance Abuse, National Working Group on Addictions Policy released policy a discussion document which recommended, "The severity of punishment for a cannabis possession charge should be reduced. Specifically, cannabis possession should be converted to a civil violation under the Contraventions Act." The paper further noted that, "The available evidence indicates that removal of jail as a sentencing option would lead to considerable cost savings without leading to increases in rates of cannabis use."

The World Health Organization noted that, while some studies indicate that adolescents who use marijuana might be more likely to drop out of high school and experience job instability in young adulthood, "the apparent strength of these cross-sectional studies ... has been exaggerated because those adolescents who are most likely to use cannabis have lower academic aspirations and poorer high school performance prior to using cannabis, than their peers who do not."

The U.S. Penal Code violations for marijuana and possible sentences:

Violation: "1000 kilograms or more of a mixture or substance containing a detectable amount of marihuana, or 1,000 or more marihuana plants regardless of weight."
Sentence: not "less than 10 years or more than life" "No person sentenced under this subparagraph shall be eligible for parole during the term of imprisonment imposed therein."

Violation: "100 kilograms or more of a mixture or substance containing a detectable amount of marihuana, or 100 or more marihuana plants regardless of weight."
Sentence: not "less than 5 years and not more than 40 years" "No person sentenced under this subparagraph shall be eligible for parole during the term of imprisonment imposed therein."

Violation: "less than 50 kilograms of marihuana, except in the case of 50 or more marihuana plants regardless of weight, 10 kilograms of hashish, or one kilogram of hashish oil"
Sentence: "not more than 5 years, a fine not to exceed the greater of that authorized in accordance with the provisions of title 18 or $250,000 if the defendant is an individual or $1,000,000 if the defendant is other than an individual, or both."

"Tetrahydrocannabinol is a very safe drug. Laboratory animals (rats, mice, dogs, monkeys) can tolerate doses of up to 1,000 mg/kg (milligrams per kilogram). This would be equivalent to a 70 kg person swallowing 70 grams of the drug -- about 5,000 times more than is required to produce a high. Despite the widespread illicit use of cannabis there are very few if any instances of people dying from an overdose. In Britain, official government statistics listed five deaths from cannabis in the period 1993-1995 but on closer examination these proved to have been deaths due to inhalation of vomit that could not be directly attributed to cannabis (House of Lords Report, 1998). By comparison with other commonly used recreational drugs these statistics are impressive."

"Although marijuana grown in the United States was once considered inferior because of a low concentration of THC, advancements in plant selection and cultivation have resulted in higher THC-containing domestic marijuana. In 1974, the average THC content of illicit marijuana was less than one percent. Today most commercial grade marijuana from Mexico/Columbia and domestic outdoor cultivated marijuana has an average THC content of about 4 to 6 percent. Between 1998 and 2002, NIDA-sponsored Marijuana Potency Monitoring System (MPMP) analyzed 4,603 domestic samples. Of those samples, 379 tested over 15 percent THC, 69 samples tested between 20 and 25 percent THC and four samples tested over 25 percent THC."

"Statements in the popular media that the potency of cannabis has increased by ten times or more in recent decades are not support by the data from either the USA or Europe. As discussed in the body of this report, systematic data are not available in Europe on long-term trends and analytical and methodological issues complicate the interpretation of the information that is available. Data are stronger for medium and short-term trends where no major differences are apparent in Europe, although some modest increases are found in some countries. The greatest long-term changes in potency appear to have occurred in the USA. It should be noted here that before 1980 herbal cannabis potency in the USA was, according to the available data, very low by European standards."

According to the federal Potency Monitoring Project, the average potency of marijuana has increased very little since the 1980s. The Project reports that in 1985, the average THC content of commercial-grade marijuana was 2.84%, and the average for high-grade sinsemilla in 1985 was 7.17%. In 1995, the potency of commercial-grade marijuana averaged 3.73%, while the potency of sinsemilla in 1995 averaged 7.51%. In 2001, commercial-grade marijuana averaged 4.72% THC, and the potency of sinsemilla in 2001 averaged 9.03%. In the period Dec. 16, 2007 through March 15, 2008, the potency of commercial-grade marijuana varied from 2.14% THC for "loose leaf," 6.4% for "kilobricks," and 7.16% THC for "buds." The potency of sinsemilla in that period averaged about 10.7% THC.

Marijuana - Statistics

"The global number of people who used cannabis at least once in 2007 is estimated to be between 143 and 190 million persons. The highest levels of use remain in the established markets of North America and Western Europe, although there are signs from recent studies that the levels of use are declining in developed countries, particularly among young people."

"Cannabis remains by far the most commonly used drug in the world. An estimated 162 million people used cannabis in 2004, equivalent to some 4 per cent of the global population age 15-64. In relative terms, cannabis use is most prevalent in Oceania, followed by North America and Africa. While Asia has the lowest prevalence expressed as part of the population, in absolute terms it is the region that is home to some 52 million cannabis users, more than a third of the estimated total. The next largest markets, in absolute terms, are Africa and North America."

Although people may think that the Drug War targets drug smugglers and 'King Pins,' in 2008, 49.8 percent (half) of the 1,702,537 total arrests for drug abuse violations were for marijuana -- a total of 847,863. Of those, 754,224 people were arrested for marijuana possession alone. By contrast in 2000 a total of 734,497 Americans were arrested for marijuana offenses, of which 646,042 were for possession alone.

Marijuana and Driving

"We found only limited evidence to support the claim that cannabis use increases accident risk. Participants who had driven under the influence of cannabis in the previous year appeared to be no more likely than drug-free drivers to report that they had had an accident in the previous 12 months. Prima facie, this would seem to suggest that cannabis-intoxicated driving is not a risk factor for non-fatal accidents. In this sense, the results would support those of Longo et al. (2000b) who found no relationship between recent cannabis use and driver culpability for non-fatal accidents."

"Both Australian studies suggest cannabis may actually reduce the responsibility rate and lower crash risk. Put another way, cannabis consumption either increases driving ability or, more likely, drivers who use cannabis make adjustments in driving style to compensate for any loss of skill (Drummer, 1995). This is consistent with simulator and road studies that show drivers who consumed cannabis slowed down and drove more cautiously (see Ward & Dye, 1999; Smiley, 1999. This compensation could help reduce the probability of being at fault in a motor vehicle accident since drivers have more time to respond and avoid a collision. However, it must be noted that any behavioral compensation may not be sufficient to cope with the reduced safety margin resulting from the impairment of driver functioning and capacity."

"Both simulator and road studies showed that relative to alcohol use alone, participants who used cannabis alone or in combination with alcohol were more aware of their intoxication. Robbe (1998) found that participants who consumed 100 g/kg of cannabis rated their performance worse and the amount of effort required greater compared to those who consumed alcohol (0.05 BAC). Ramaekers et al. (2000) showed that cannabis use alone and in combination with alcohol consumption increased self-ratings of intoxication and decreased self-ratings of performance. Lamers and Ramaekers (2001) found that cannabis use alone (100 g/kg) and in combination with alcohol consumption resulted in lower ratings of alertness, greater perceptions of effort, and worse ratings of performance."

"Cannabis is only considered a risk factor for traffic accidents if drivers operate vehicles after consuming the drug. Robbe (1994) found that 30% to 90% of his participants were willing to drive after consuming a typical dose of cannabis. This is consistent with a recent Australian survey in which more than 50% of users drove after consuming cannabis (Lenne, Fry, Dietze, & Rumbold, 2000). A self administered questionnaire given to 508 students in grades 10 to 13 in Ontario, Canada, found that 19.7% reported driving within an hour after using cannabis (Adlaf, Mann, & Paglia, 2003)."

"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."

"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."

According to a literature review of the effects of alcohol on driving, "As with cannabis, alcohol use increased variability in lane position and headway (Casswell, 1979; Ramaekers et al., 2000; Smiley et al., 1981; Stein et al., 1983) but caused faster speeds (Casswell, 1977; Krueger & Vollrath, 2000; Peck et al., 1986; Smiley et al., 1987; Stein et al., 1983). Some studies also showed that alcohol use alone and in combination with cannabis affected visual search behavior (Lamers & Ramaekers, 2001; Moskowitz, Ziedman, & Sharma, 1976). Alcohol consumption combined with cannabis use also worsened driver performance relative to use of either substance alone. Lane position and headway variability were more exaggerated (Attwood et al., 1981; Ramaekers et al., 2000; Robbe, 1998) and speeds were faster (Peck et al., 1986).

"Both simulator and road studies showed that relative to alcohol use alone, participants who used cannabis alone or in combination with alcohol were more aware of their intoxication. Robbe (1998) found that participants who consumed 100 g/kg of cannabis rated their performance worse and the amount of effort required greater compared to those who consumed alcohol (0.05 BAC). Ramaekers et al. (2000) showed that cannabis use alone and in combination with alcohol consumption increased self-ratings of intoxication and decreased self-ratings of performance. Lamers and Ramaekers (2001) found that cannabis use alone (100 g/kg) and in combination with alcohol consumption resulted in lower ratings of alertness, greater perceptions of effort, and worse ratings of performance."

A literature review of the effects of cannabis on driving found, "Another paradigm used to assess crash risk is to use cross-sectional surveys of reported nonfatal accidents that can be related to the presence of risk factors, such as alcohol and cannabis consumption. Such a methodology was employed in a provocative dissertation by Laixuthai (1994). This study used data from two large surveys that were nationally representative of high school students in the United States during 1982 and 1989. Results showed that cannabis use was negatively correlated with nonfatal accidents, but these results can be attributed to changes in the amount of alcohol consumed. More specifically, the decriminalization of cannabis and the subsequent reduction in penalty cost, as well as a reduced purchase price of cannabis, made cannabis more appealing and affordable for young consumers. This resulted in more cannabis use, which substituted for alcohol consumption, leading to less frequent and less heavy drinking. The reduction in the amount of alcohol consumed resulted in fewer nonfatal accidents."

"When compared to alcohol, cannabis is detected far less often in accident-involved drivers. Drummer et al. (2003) cited several studies and found that alcohol was detected in 12.5% to 79% of drivers involved in accidents. With regard to crash risk, a large study conducted by Borkenstein, Crowther, Shumate, Zeil and Zylman (1964) compared BAC in approximately 6,000 accident-involved drivers and 7,600 nonaccident controls. They determined the crash risk for each BAC by comparing the number of accident-involved drivers with detected levels of alcohol at each BAC to the number of nonaccident control drivers with the same BAC. They found that crash risk increased sharply as BAC increased. More specifically, at a BAC of 0.10, drivers were approximately five times more likely to be involved in an accident.

"Similar crash risk results were obtained when data for culpable drivers were evaluated. Drummer (1995) found that drivers with detected levels of alcohol were 7.6 times more likely to be culpable. Longo et al. (2000) showed that drivers who tested positive for alcohol were 8.0 times more culpable, and alcohol consumption in combination with cannabis use produced an odds ratio of 5.4. Similar results were also noted by Swann (2000) and Drummer et al. (2003)."

According to a literature review on the effects of cannabis on driving, "Most of the research on cannabis use has been conducted under laboratory conditions. The literature reviews by Robbe (1994), Hall, Solowij, and Lemon (1994), Border and Norton (1996), and Solowij (1998) agreed that the most extensive effect of cannabis is to impair memory and attention. Additional deficits include problems with temporal processing, (complex) reaction times, and dynamic tracking. These conclusions are generally consistent with the psychopharmacological effects of cannabis mentioned above, including problems with attention, memory, motor coordination, and alertness.

"A meta-analysis by Krüger and Berghaus (1995) profiled the effects of cannabis and alcohol. They reviewed 197 published studies of alcohol and 60 studies of cannabis. Their analysis showed that 50% of the reported effects were significant at a BAC of 0.073 g/dl and a THC level of 11 ng/ml. This implies that if the legal BAC threshold for alcohol is 0.08 g/dl, the corresponding level of THC that would impair the same percentage of tests would be approximately 11 ng/ml."

"Several studies have examined cannabis use in driving simulator and on-road situations. The most comprehensive review was done by Smiley in 1986 and then again in 1999. Several trends are evident and can be described by three general performance characteristics:

"1. Cannabis increased variability of speed and headway as well as lane position (Attwood, Williams, McBurney, & Frecker, 1981; Ramaekers, Robbe, & O'Hanlon, 2000; Robbe, 1998; Sexton et al., 2000; Smiley, Moskowitz, & Zeidman, 1981; Smiley, Noy, & Tostowaryk, 1987). This was more pronounced under high workload and unexpected conditions, such as curves and wind gusts.

"2. Cannabis increased the time needed to overtake another vehicle (Dott, 1972 [as cited in Smiley, 1986]) and delayed responses to both secondary and tracking tasks (Casswell, 1977; Moskowitz, Hulbert, & McGlothlin,
1976; Sexton et al., 2000; Smiley et al., 1981).

"3. Cannabis resulted in fewer attempts to overtake another vehicle(Dott, 1972) and larger distances required to pass (Ellingstad et al., 1973 [as cited in Smiley, 1986]). Evidence of increased caution also included slower speeds (Casswell, 1977; Hansteen, Miller, Lonero, Reid, & Jones, 1976; Krueger & Vollrath, 2000; Peck, Biasotti, Boland, Mallory, & Reeve, 1986; Sexton et al., 2000; Smiley et al., 1981; Stein, Allen, Cook, & Karl, 1983) and larger headways (Robbe, 1998; Smiley et al., 1987)."

"The results of our meta-analytic study failed to reveal a substantial, systematic effect of long-term, regular cannabis consumption on the neurocognitive functioning of users who were not acutely intoxicated. For six of the eight neurocognitive ability areas that were surveyed. the confidence intervals for the average effect sizes across studies overlapped zero in each instance, indicating that the effect size could not be distinguished from zero. The two exceptions were in the domains of learning and forgetting."

Marijuana - Effects

"These results can be interpreted in several ways. A statistically reliable negative effect was observed in the domain of learning and forgetting, suggesting that chronic long-term cannabis use results in a selective memory defect. While the results are compatible with this conclusion, the effect size for both domains was of a very small magnitude. The "real life" impact of such a small and selective effect is questionable. In addition, it is important to note that most users across studies had histories of heavy longterm cannabis consumption. Therefore, these findings are not likely to generalize to more limited administration of cannabis compounds, as would be seen in a medical setting."

"There are health risks of cannabis use, most particularly when it is used daily over a period of years or decades. Considerable uncertainty remains about whether these effects are attributable to cannabis use alone, and about what the quantitative relationship is between frequency, quantity and duration of cannabis use and the risk of experiencing these effects.

On existing patterns of use, cannabis poses a much less serious public health problem than is currently posed by alcohol and tobacco in Western societies."

The authors of a 1998 World Health Organization report comparing marijuana, alcohol, nicotine and opiates quote the Institute of Medicine's 1982 report stating that there is no evidence that smoking marijuana "exerts a permanently deleterious effect on the normal cardiovascular system."

Some claim that cannabis use leads to "adult amotivation." The World Health Organization report addresses the issue and states, "it is doubtful that cannabis use produces a well defined amotivational syndrome." The report also notes that the value of studies which support the "adult amotivation" theory are "limited by their small sample sizes" and lack of representative social/cultural groups.

"A review of the literature suggests that the majority of cannabis users, who use the drug occasionally rather than on a daily basis, will not suffer any lasting physical or mental harm. Conversely, as with other 'recreational' drugs, there will be some who suffer adverse consequences from their use of cannabis. Some individuals who have psychotic thought tendencies might risk precipitating psychotic illness. Those who consume large doses of the drug on a regular basis are likely to have lower educational achievement and lower income, and may suffer physical damage to the airways. They also run a significant risk of becoming dependent upon continuing use of the drug. There is little evidence, however, that these adverse effects persist after drug use stops or that any direct cause and effect relationships are involved."

The Christchurch Press reported on March 22, 2005, that "The lead researcher in the Christchurch study, Professor David Fergusson, said the role of cannabis in psychosis was not sufficient on its own to guide legislation. 'The result suggests heavy use can result in adverse side-effects,' he said. 'That can occur with ( heavy use of ) any substance. It can occur with milk.' Fergusson's research, released this month, concluded that heavy cannabis smokers were 1.5 times more likely to suffer symptoms of psychosis that non-users. The study was the latest in several reports based on a cohort of about 1000 people born in Christchurch over a four-month period in 1977. An effective way to deal with cannabis use would be to incrementally reduce penalties and carefully evaluate its impact, Fergusson said. 'Reduce the penalty, like a parking fine. You could then monitor ( the impact ) after five or six years. If it did not change, you might want to take another step.'

A Johns Hopkins study published in May 1999, examined marijuana's effects on cognition on 1,318 participants over a 15 year period. Researchers reported "no significant differences in cognitive decline between heavy users, light users, and nonusers of cannabis." They also found "no male-female differences in cognitive decline in relation to cannabis use." "These results ... seem to provide strong evidence of the absence of a long-term residual effect of cannabis use on cognition," they concluded.

According to research published in the journal Addiction, "First, the use of cannabis and rates of psychotic symptoms were related to each other, independently of observed/non-observed fixed covariates and observed time dynamic factors (Table 2). Secondly, the results of structural equation modelling suggest that the direction of causation is that the use of cannabis leads to increases in levels of psychotic symptoms rather than psychotic symptoms increasing the use of cannabis. Indeed, there is a suggestion from the model results that increases in psychotic symptoms may inhibit the use of cannabis."

"Current marijuana use had a negative effect on global IQ score only in subjects who smoked 5 or more joints per week. A negative effect was not observed among subjects who had previously been heavy users but were no longer using the substance. We conclude that marijuana does not have a long-term negative impact on global intelligence. Whether the absence of a residual marijuana effect would also be evident in more specific cognitive domains such as memory and attention remains to be ascertained."

"Although the heavy current users experienced a decrease in IQ score, their scores were still above average at the young adult assessment (mean 105.1). If we had not assessed preteen IQ, these subjects would have appeared to be functioning normally. Only with knowledge of the change in IQ score does the negative impact of current heavy use become apparent."

"In conclusion, our meta-analysis of studies that have attempted to address the question of longer term neurocognitive disturbance in moderate and heavy cannabis users has failed to demonstrate a substantial, systematic, and detrimental effect of cannabis use on neuropsychological performance. It was surprising to find such few and small effects given that most of the potential biases inherent in our analyses actually increased the likelihood of finding a cannabis effect."

The Canadian Senate's Special Committee on Illegal Drugs recommended in its 2002 final report on cannabis policy that "the Government of Canada amend the Controlled Drugs and Substances Act to create a criminal exemption scheme. This legislation should stipulate the conditions for obtaining licenses as well as for producing and selling cannabis; criminal penalties for illegal trafficking and export; and the preservation of criminal penalties for all activities falling outside the scope of the exemption scheme."

"Our conclusion is that the present law on cannabis produces more harm than it prevents. It is very expensive of the time and resources of the criminal justice system and especially of the police. It inevitably bears more heavily on young people in the streets of inner cities, who are also more likely to be from minority ethnic communities, and as such is inimical to police-community relations. It criminalizes large numbers of otherwise law-abiding, mainly young, people to the detriment of their futures. It has become a proxy for the control of public order; and it inhibits accurate education about the relative risks of different drugs including the risks of cannabis itself."

When examining the relationship between marijuana use and violent crime, the National Commission on Marihuana and Drug Abuse concluded, "Rather than inducing violent or aggressive behavior through its purported effects of lowering inhibitions, weakening impulse control and heightening aggressive tendencies, marihuana was usually found to inhibit the expression of aggressive impulses by pacifying the user, interfering with muscular coordination, reducing psychomotor activities and generally producing states of drowsiness lethargy, timidity and passivity."

When examining the health affects of marijuana use, the National Commission on Marihuana and Drug Abuse concluded, "A careful search of the literature and testimony of the nation's health officials has not revealed a single human fatality in the United States proven to have resulted solely from ingestion of marihuana. Experiments with the drug in monkeys demonstrated that the dose required for overdose death was enormous and for all practical purposes unachievable by humans smoking marihuana. This is in marked contrast to other substances in common use, most notably alcohol and barbiturate sleeping pills. The WHO reached the same conclusion in 1995.

Commissioned by President Nixon in 1972, the National Commission on Marihuana and Drug Abuse concluded that "Marihuana's relative potential for harm to the vast majority of individual users and its actual impact on society does not justify a social policy designed to seek out and firmly punish those who use it. This judgment is based on prevalent use patterns, on behavior exhibited by the vast majority of users and on our interpretations of existing medical and scientific data. This position also is consistent with the estimate by law enforcement personnel that the elimination of use is unattainable."

"Nevertheless, when considering all 15 studies (i.e., those that met both strict and more relaxed criteria) we only noted that regular cannabis users performed worse on memory tests, but that the magnitude of the effect was very small. The small magnitude of effect sizes from observations of chronic users of cannabis suggests that cannabis compounds, if found to have therapeutic value, should have a good margin of safety from a neurocognitive standpoint under the more limited conditions of exposure that would likely obtain in a medical setting."

In an ethnographic study of adolescents who were regular marijuana users, researchers at the University of British Columbia, concluded, "Thematic analysis revealed that these teens differentiated themselves from recreational users and positioned their use of marijuana for relief by emphasizing their inability to find other ways to deal with their health problems, the sophisticated ways in which they titrated their intake, and the benefits that they experienced. These teens used marijuana to gain relief from difficult feelings (including depression, anxiety and stress), sleep difficulties, problems with concentration and physical pain. Most were not overly concerned about the risks associated with using marijuana, maintaining that their use of marijuana was not 'in excess' and that their use fit into the realm of 'normal.'

Conclusion: Marijuana is perceived by some teens to be the only available alternative for teens experiencing difficult health problems when medical treatments have failed or when they lack access to appropriate health care."

"Nonetheless, and contrary to our expectations, we found no positive associations between marijuana use and lung or UAT cancers ... Despite several lines of evidence suggesting the biological plausibility of marijuana use being carcinogenic (1), it is possible that marijuana use does not increase cancer risk, as suggested in the recent commentary by Melamede."

Adolescents - Monitoring the Future Report

"A study of the effects of decriminalization by several states during the late 1970s found no evidence of any impact on the use of marijuana among young people, nor on attitudes and beliefs concerning its use. (85) However, it should be noted that decriminalization falls well short of the full legalization posited in the questions here. Moreover, the situation today is very different than it was in the late 1970s, with much more peer disapproval and more rigorous enforcement of drug laws. More recent studies suggest that there may be an impact of decriminalization, such that 'youths living in decriminalized states are significantly more likely to report currently using marijuana.'"

"Most 12th graders felt that they would be little affected personally by the legalization of either the sale or the use of marijuana. About three fifths (61%) of the respondents said that they would not use the drug even if it were legal to buy and use, while others indicated they would use it about as often as they do now (15%) or less often (1.4%). Only 5.5% said they would use it more often than they do at present, while another 8.9% thought they would try it. (Nine percent said they did not know how their behavior would be affected if marijuana were legalized.) Still, this amounts to 14.4%, or about one in seven who state that they would try marijuana, or their use would increase, if marijuana were legalized."

"As shown in Table 8-8, about equal proportions of 12th graders in 2008 believed that marijuana use should be (a) entirely legal (29%); (b) a minor violation like a parking ticket, but not a crime (30%); or (c) a crime (28%). (The remaining 13% said they 'don’t know.')

"Asked whether they thought it should be legal to sell marijuana if it were legal to use it, just over half (56%) said 'yes.' However, four fifths of those answering 'yes' (46% of all respondents) would permit the sale only to adults. Only a small minority (10%) favored the sale to anyone, regardless of age, while 31% said that sale should not be legal even if use were made legal, and 13% said they 'don’t know.'"

"Ever since the study began in 1975, between 83% and 90% of seniors each year have said that they could get marijuana fairly easily or very easily if they wanted some. It has been considerably less accessible to younger adolescents. Still, in 2008 nearly two fifths of 8th graders (39%) and two thirds of 10th graders (67%) reported it as being accessible. This compares to 84% for seniors."

"Annual marijuana prevalence peaked among 12th graders in 1979 at 51%, following a rise that began during the 1960s. Then use declined fairly steadily for 13 years, bottoming at 22% in 1992—a decline of more than half. The 1990s, however, saw a resurgence of use. After a considerable increase (one that actually began among 8th graders a year earlier than among 10th and 12th graders), annual prevalence rates peaked in 1996 at 8th grade and in 1997 at 10th and 12th grades. After 1996 there was a continuing gradual decline among 8th graders through 2007, with a pause in 2005. Considering the small increase in 2008, use now is down from the 1996 peak level by about two fifths. In the upper grades, only a very modest decline occurred between 1997 and 2002, followed by a continuing gradual decline. In 10th grade, the decline continued through 2008; while for 12th graders, it halted in 2007 and then use rose slightly in 2008."

Researchers examining the effectiveness of the ONDCP's Youth Anti-Drug Media Campaign reported in late 2003 that, "The NSPY [National Survey of Parents and Youth] did not find significant reductions in marijuana use either leading up to or after the Marijuana campaign for youth 12 to 18 years old between 2002 and 2003. Indeed there was evidence for an increase in past month and past year use among the target audience of 14- to 16-year-olds, although it appears that the increase was already in place in the last half of 2002, before the launch of the Marijuana Initiative. It will be worthwhile to track whether the nonsignificant decline from the second half of 2002 through the first half of 2003 is the beginning of a true trend. There was a significant decrease in lifetime marijuana use among youth 16 to 18 years of age from 2002 to 2003; however, since this significant decrease was not replicated in either the directly relevant past year or past month time periods, it is difficult to ascribe the change to the campaign."

Institute of Medicine - Marijuana and Medicine: Assessing the Science Base - 1999

"At this point, our knowledge about the biology of marijuana and cannabinoids allows us to make some general conclusions:

· Cannabinoids likely have a natural role in pain modulation, control of movement, and memory.

· The natural role of cannabinoids in immune systems is likely multi-faceted and remains unclear.

· The brain develops tolerance to cannabinoids.

· Animal research demonstrates the potential for dependence, but this potential is observed under a narrower range of conditions than with benzodiazepines, opiates, cocaine, or nicotine.

· Withdrawal symptoms can be observed in animals but appear to be mild compared to opiates or benzodiazepines, such as diazepam (Valium)."

In March 1999, the Institute of Medicine issued a report on various aspects of marijuana, including the so-called Gateway Theory (the theory that using marijuana leads people to use harder drugs like cocaine and heroin). The IOM stated: "There is no conclusive evidence that the drug effects of marijuana are causally linked to the subsequent abuse of other illicit drugs."

A 1999 federal report conducted by the Institute of Medicine found that, "For most people, the primary adverse effect of acute marijuana use is diminished psychomotor performance. It is, therefore, inadvisable to operate any vehicle or potentially dangerous equipment while under the influence of marijuana, THC, or any cannabinoid drug with comparable effects."

The Institute of Medicine's 1999 report on marijuana explained that marijuana has been mistaken for a gateway drug in the past because "Patterns in progression of drug use from adolescence to adulthood are strikingly regular. Because it is the most widely used illicit drug, marijuana is predictably the first illicit drug most people encounter. Not surprisingly, most users of other illicit drugs have used marijuana first. In fact, most drug users begin with alcohol and nicotine before marijuana, usually before they are of legal age."