Right: On August 10, 2023, Greens Senator David Shoebridge introduced the Legalising Cannabis Bill, seeking to establish a national framework for legalizing and regulating cannabis across Australia.
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Arguments against legalising cannabis
1. Legalising cannabis / marijuana is a physical health riskThose who oppose the legalisation of marijuana noted that there is increasing data linking marijuana use with physical ill health.
A range of adverse health effects have been linked to marijuana use. A report from the American Addiction Centers updated on June 23, 2023, noted that marijuana use had been associated with respiratory difficulties. The report notes 'Marijuana smoke can irritate the respiratory tract-including the throat and lungs. Frequent use over a prolonged period increases the risk of problems such as cough, chronic bronchitis, increased risk and frequency of pneumonia, and other lung illnesses.'
Smoked marijuana delivers harmful substances, including many of the same toxins and carcinogens (cancer-causing chemicals) found in tobacco smoke, which are harmful to the lungs and cardiovascular system. More research is needed to understand the effects marijuana might have on lung and other respiratory cancers. Medical News Today has also reported that other studies have demonstrated aggravation of existing lung conditions, such as asthma, when a person smokes it. A weakened immune system has also been noted because of tetrahydrocannabinol, which is the main psychoactive chemical in cannabis. Marijuana use, particularly smoking, has also been linked to cardiac issues. The United States Centers for Disease Control and Prevention has noted, 'Marijuana can make the heart beat faster and can make blood pressure higher immediately after use.1,2 It could also lead to increased risk of stroke, heart disease, and other vascular diseases.3-7 Most of the scientific studies linking marijuana to heart attacks and strokes are based on reports from people who smoked marijuana (as opposed to other methods of using it). Smoked marijuana delivers tetrahydrocannabinol (THC) and other cannabinoids to the body. Marijuana smoke also delivers many of the same substances researchers have found in tobacco smoke-these substances are harmful to the cardiovascular system.'
Marijuana smoking has also been noted to cause several short-term ill effects. The short-term effects of cannabis on the body can include damaged blood vessels caused by the smoke, decreased blood pressure, which can cause people to faint or pass out, and increased heart rate, which can be a danger for people with heart conditions and can lead to an increased risk.
of heart attack.
It has also been noted that ingesting cannabis rather than smoking the substance poses a different set of health risks, including a greater risk of poisoning. Unlike smoked marijuana, edibles can take from 30 minutes to two hours to take effect, so some people may eat too much, which can lead to poisoning and/or serious injury. Ingestion can also cause intoxicating effects that last longer than expected, depending on the amount ingested, the last food eaten, and medications or alcohol used at the same time. In addition, ingested marijuana can have unpredictable effects. The amount of tetrahydrocannabinol (THC), or the concentration or strength, is very difficult to measure and is often unknown in edible products. Many people who use edibles can be caught off-guard by their strength and long-lasting effects.
Symptoms of cannabis poisoning can include chest pain, rapid heartbeat, nausea/vomiting, psychotic episode, respiratory depression, severe anxiety and/or panic attack. A systematic review of 30 studies from the United States, Canada and Thailand shows legalising cannabis is associated with increased rates of cannabis poisoning. 2. Legalising cannabis is a mental health risk
Opponents of legalising cannabis argue that increased use of the drug will result in an increase in the incidence of schizophrenia and other forms of psychosis, particularly among those who take up the habit in adolescence.
'Psychosis' is a term used to describe several psychological symptoms that affect understanding or perception of reality. It commonly occurs in late adolescence or early adulthood and affects around three in every 100 people in Australia.
Symptoms of psychosis include confused thinking, delusions, hallucinations and changed behaviours and feelings. During an episode of psychosis, a person's thoughts become confused. Words and ideas lose their meaning or take on meanings that make no sense. These disturbances in thinking can affect a person's ability to concentrate, remember things and make plans. Confused thinking can continue, even after the psychotic episode has ended. Among the delusions that may manifest during a psychotic episode are paranoid delusions where a person believes he or she is being persecuted, abused, or being spied upon. Also common are depression delusions in which, for example, a suffer may believe he or she is guilty of some awful crime. Suffers may also experience auditory or visual hallucinations, believing they can ear or see things that are not there. Such episodes may also be accompanied by strong feeling of isolation or detachment, or perhaps mood swings where the person switches rapidly from extreme excitement to depression. The relationship between cannabis use and risk of developing symptoms of psychosis has been established in many different review articles over years. SANE Australia, a leading national health organisation for people with complex mental health issues, has noted that cannabis use, even in small doses, can cause paranoia, delusions and hallucinations in people who do not already have a mental illness. Cannabis use can also trigger or worsen psychotic symptoms in people living with an illness like schizophrenia, even when their illness is otherwise stable and responding well to treatment.
It has also been claimed that using cannabis earlier in life increases the likelihood of developing psychosis. According to several studies, people who begin using cannabis in adolescence are more likely to experience symptoms of psychosis or receive a diagnosis of schizophrenia later in life. Cannabis use could also influence the age at which a person begins to experience symptoms of psychosis. A 2011 review of 83 studies found support for a link between early cannabis use and earlier onset of psychosis.
Michael T. Compton, a professor of clinical psychiatry at the Columbia University College of Physicians and Surgeons, has stated, 'Very detailed and rigorous retrospective data [have been] collected on the onset of... psychotic symptoms, as well as the initiation and escalation of nicotine, alcohol, marijuana, and other drug use... These findings suggest that adolescent/premorbid marijuana use is not only a risk factor for the later development of primary psychotic disorders... but is also a risk factor for an earlier onset of those disorders.' Regarding a link between legalising cannabis and an increased incidence psychosis it has been noted that as the number of cannabis dispensaries rose in Colorado after legalisation, the rates of psychosis-related hospital visits increased across all counties in Colorado.
The International Narcotics Control Board issued a media release on March 9, 2023, warning that in all jurisdictions where cannabis has been legalized, data show that cannabis-related health problems have increased. It pointed out that between 2000 and 2018, 'global medical admissions related to cannabis dependence and withdrawal increased eight-fold. Admissions for cannabis-related psychotic disorders have quadrupled worldwide.' 3. Marijuana use can negatively affect cognition
There are numerous scientific studies which have demonstrated that marijuana use, both short- and long-term, can impair the users mental functioning.
Studies going back over sixty years and replicated through to the present have demonstrated the harmful effect of marijuana on users' cognitive functioning. Researchers first began studying the acute effects of cannabis on neuropsychological functioning in the 1970s and consistently found disruptions in learning and memory functions. For more than 40 years, researchers have shown that cannabis consumption impairs working memory, or the ability to hold and manipulate information and remember it following a short delay. This finding has been replicated in current research. A 2001 study of chronic cannabis users found that acute intoxication resulted in significant impairment in working memory, and those subjects receiving a higher dose took significantly longer to complete the test tasks.
A 2006 study examined attentional capacities in "real world" situations; that is, right before work and immediately after work, at both the beginning and end of the work week. They found that, compared with non-cannabis-using controls, cannabis subjects had significantly impaired attention both at the beginning of the work week and at the end, which was significantly correlated with the subjects' duration of cannabis use. Short- and long-term use of marijuana has been shown to have negative effects on mental functioning; however, the more sustained the use and the greater the amount consumed increase the extent of the harm done. Research published in 2022 investigated the cognitive effects of long-term cannabis use by studying a subject population of nearly 1,000 New Zealanders from age three to age 45. Some of this group grew up to use marijuana, others did not. The research team discovered that individuals who used cannabis long-term (for several years or more) and heavily (at least weekly, though a majority in their study used more than four times a week) exhibited impairments across several domains of cognition. Relative to the normative IQ of 100, long-term cannabis users had average IQ as children (mean=99.3) but below-average IQ as adults (mean=93.8). Their mean 5.5-point childhood-to-adulthood IQ decline was significantly larger than that observed among lifelong cannabis nonusers. The more frequently an individual used cannabis, the greater the resulting cognitive impairment, suggesting a potential causative link.
Research suggests that adolescents using cannabis can suffer particular harm to their neurological development. Adolescent brain development that continues into the early adulthood years focuses on fine-tuning neural pathways that contribute to brain maturity and developing the prefrontal cortex, which is responsible for assessing situations, making sound decisions, and controlling emotions and impulses. The brain's endocannabinoid system, a signaling system in the body and brain, plays a critical role during these developmental changes. Tetrahydrocannabinol (THC) and other chemicals bind to the endocannabinoid receptors, causing dysregulation of this neurotransmitter system which could potentially result in long-term neurodevelopmental changes. Studies exploring the long-term effects of adolescent marijuana use on cognition, brain structure, and brain functioning compared to adults, suggest that the adolescent brain is far more sensitive to the chemicals in marijuana than the adult brain. Additionally, research indicates that chronic marijuana use during adolescence can lead to a loss of IQ that is not recovered even if the individual stops marijuana use in adulthood.
4. Marijuana negatively affects driver performance leading to increased accidents, injuries, and fatalities. It also increases the likelihood of workplace accidents.
Those who oppose the legalisation of marijuana claim that this increased use of the drug will lead to a significant increase in accidents on the road and in the workplace.
Numerous studies over decades have demonstrated why cannabis consumption increases the likelihood of road accidents. A 2011 overview published in the British Columbia Medical Journal noted, 'There is clear evidence that cannabis, like alcohol, impairs the psychomotor skills required for safe driving. Cannabis intoxication slows reaction time and impairs automated tasks such as tracking ability (staying within a lane) or monitoring the speedometer. In simulator studies, high doses of cannabis caused drivers to "crash" into a sudden obstacle more often.'
Similar conclusions have been drawn from an Australian overview of the effects of marijuana on driving performance published by Drug-Free Australia. The Australian overview stated, 'Attentiveness, vigilance, perception of time and speed, and use of acquired knowledge are all affected by marijuana; in fact, a meta-analysis of 60 studies concluded that marijuana causes impairment in every performance area that can reasonably be connected with safe driving of a vehicle, such as tracking, motor coordination, visual functions, and particularly complex tasks that require divided attention, although studies on marijuana's effects on reaction time have been contradictory. Similar conclusions have been reached by other reviewers. Worse still, marijuana and alcohol, when used together, have additive or even multiplicative effects on impairment. Consequently, on the basis of cognitive studies, it seems reasonable to propose that smoking marijuana may increase the risk of having a fatal traffic accident.'
Statistical data of the incidence of traffic accidents among marijuana users supports studies showing the physiological effect of marijuana consumption on driver and pedestrian competence. A recent Australian study has indicated that cannabis-related accidents are a significant cause of death among marijuana users in this country. The study released in April 2020 found that 559 cannabis-related deaths were identified between 2000 and 2018. The leading cause of death was accidental injury (30 percent), with motor vehicle accidents being the leading cause of accidental injury deaths (75 percent). Emma Zahra, the lead author of the study stated, 'One in five (of the cannabis-related) motor vehicle accident deaths were pedestrians, highlighting that acute cannabis and polysubstance intoxication can affect information processing and perception of risk.' The study indicated that the risk was increased when users combined alcohol consumption with cannabis intake. Zahra has noted, 'Past research has highlighted that polysubstance use is common and increases the risk of harm. When cannabis and alcohol are consumed simultaneously the risk increases considerably.'
Victorian road fatalities demonstrate the same cannabis connection as seen in Australia as a whole. Vic Road has indicated that drug-usage is a major contributor to road accidents. The Vic Roads website claims, 'In the last five years, around 41 per cent of all driver and motorcyclist fatalities who were tested, had illicit drugs in their system. Drivers who take illicit drugs are much more likely to be involved in a crash than drug-free drivers and are often responsible for these crashes.'
Data on Victorian drivers killed on the roads between 2012 and 2014 indicated that marijuana was the most implicated of all illegal drugs. Blood samples from drivers and riders killed in road crashes in Victoria over this period showed that THC (the active ingredient in marijuana) was present in 15 percent of deceased drivers and riders, while amphetamine (ecstasy, speed and ice) was present in the blood samples of 10 per cent of deceased drivers and riders. Other illegal drugs were found in the bodies of two percent of those killed. Finally, as an increasing number of American States have legalised cannabis, a related increase in the number of cannabis-related road accidents has been observed. After legalisation and the launch of retail sales, there was a 5.8 percent rise in the incidence of traffic collision injuries and a 4.1 percent increase in the rate of fatal crashes among five states that have legalised recreational cannabis use for those over 21. In a comparative group of states without marijuana legalisation, the researchers did not see any rise during the same period.
United States data also links workplace accidents with marijuana use. Increased incidence of marijuana use among those involved in workplace accidents has been noted as more American states have legalised the recreational use of marijuana. The Society for Human Resources Management has noted, 'The number of drug tests performed after an accident that came up positive for marijuana grew 204 percent from 2012 to 2022, coinciding with a trend of more states legalizing recreational cannabis use. The post-accident positivity rate was 7.3 percent in 2022, up from 6.7 percent in 2021.'
5. Legalising marijuana would increase supply and use
Critics of legalising marijuana argue that legalisation leads to increased production and consumption with a rise in associated health and road safety problems. It is also claimed that it increases and consolidates the problem of marijuana addiction.
In numerous jurisdictions around the world, the legalisation of marijuana has resulted in its increased production and use. The Canadian government legalised, regulated, and restricted access to cannabis on October 17, 2018. Under federal legislation adults can possess up to 30 grams of legally produced cannabis and can grow up to four cannabis plants per household.
The minimum age for purchase and use is 18. Despite regulation, it appears that there has been a growth in production and use since the drug was legalised. Data from Statistics Canada indicates that in the first year-and-half post-legalization, the legal market expansion essentially matched illegal market contraction. However, since early 2020, increases in legal sales have dramatically outpaced decreases in illegal sales, resulting in increased overall spending.
By 2019, more than 5.1 million people nationally, or 16.8 percent of Canadians aged 15 or older, reported using cannabis in the three months before being surveyed. This was higher than the 14.9 percent (4.5 million) reporting use, on average, in 2018 (before legalisation). Professor Iain McGregor. the academic director of the Lambert initiative for cannabinoid therapeutics at the University of Sydney, has expressed reservations about the growth in marijuana production and use in Canada. He has claimed that there had been 'a race to the bottom in terms of price' after people began 'growing in bulk themselves, while eschewing the more expensive products available in street fronts'. Professor McGregor has also claimed that the same issues had been seen in New York, where there was a 'fuzziness' around what was legally being sold and what was not - leading to a cultivation boom that produced a billion-dollar 'weed mountain'. Longitudal studies showing the impact of legalising marijuana on use of the drug have demonstrated significant increases over time in many American states. Maine's regular marijuana use rate hovered around 12-13 percent between 2003 and 2009; it then increased to 14 percent in 2011, 16 percent in 2013, and 19 percent from 2014 through 2016. After legalisation in 2016, the increase continued to 22 percent in 2017 and almost 24 percent in 2018. Similarly, marijuana use in Massachusetts began increasing in 2012, several years prior to its legalisation in 2016. Maine and Massachusetts track the pattern previously seen with early legalisers (Colorado, Washington, Alaska, and Oregon) of increases in use prevalence in the few years leading up to legalization and steeper increases after.
It has been noted that in states in the United States where recreational cannabis use has been legalised, the drug is consumed 20 percent more frequently than in states that did not legalise it. Another concern is that in states where recreational cannabis has been legalised, its use among adolescents has increased. There are several studies examining cannabis use changes over time among adolescents in Washington and Oregon that have found higher rates of cannabis use after the legalisation of cannabis compared before the drug was legalised. Not only have studies revealed that legalisation leads to an increased use of marijuana, but they have also found that legalisation appears linked to more problematic use. That is, legalisation appears to be followed by an increase in drug users who have problems regulating their use and whose lives are adversely affected by their use. In a 2019 study, researchers focused on the first four American states to legalise marijuana - Colorado, Washington, Oregon, and Alaska - and divided the findings among adolescents (12 to 17), young adults (18 to 25), and older adults (26 and older). The researchers found marijuana use, frequent use, and cannabis use disorder increased more among older adults in states where marijuana was legalised than in non-legalisation states. Among older adults in legalisation states, past-month use went from 5.65 percent to 7.1 percent, past-month frequent use went from 2.13 percent to 2.62 percent, and past-year cannabis use disorder went from 0.9 to 1.23 percent.
Some early data from Colorado, one of the first two American states to legalise, supports the claim that legalisation increases the likelihood of addiction among older established users. A 2014 study of the state's legal marijuana market, conducted by the Marijuana Policy Group for the state's Department of Revenue, found the top 29.9 percent heaviest users in Colorado made up 87.1 percent of the demand for the drug.