In a little over two decades, the marijuana industry has come an incredibly long way in North America.

Back in 1995, cannabis was illegal throughout North America for medical and recreational use. Since then, we've witnessed Mexico legalize medical weed in June 2017, Canada legalize medical (2001) and recreational marijuana (2018), and observed 30 U.S. states give the green light to broad-sweeping medical cannabis laws. Of these 30 legalized states, nine also have given the thumbs-up to recreational pot, with eight allowing the sale of the drug in dispensaries to adults.

A man smelling the leaves of a potted cannabis plant that he's holding.

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The public pushes for change

What's the impetus behind this big change? If you said money, you'd be partially correct. There's certainly an incentive for local, state, provincial, and/or federal lawmakers throughout North America to consider legalizing weed. For example, the state of Colorado racked up $247 million in tax revenue from the sale of $1.51 billion in legal cannabis in 2017. Colorado is primarily putting this revenue to work by reinvesting in its education system, but is also bolstering its budgets for law enforcement and drug-abuse education programs. 

However, changing public perception has played a key role, too. National pollster Gallup found that just 25% of surveyed Americans wanted to see marijuana legalized back in 1995. As of October 2017, support for nationwide legalization had catapulted to 64%, an all-time high. Similar support can be found across other national surveys.

Favorability toward medical marijuana is even higher. An April 2018 survey from the independent Quinnipiac University found that an overwhelming 93% of respondents favored the idea of physicians being able to prescribe cannabis to patients. Comparatively, just 4% of respondents were opposed.

A doctor holding a cannabis leaf between his hands.

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Does marijuana offer benefits? The American public believes so.

With this change of perception in focus, a team of nine researchers, with funding from the National Heart, Lung, and Blood Institute, sought to get a better feel for the public's views on the risks and benefits of marijuana use. The results, which were published in July in the Annals of Internal Medicine, show that 9,003 of the 16,280 U.S. adults who were questioned responded.

The leading find was that 81% of polled adults believe marijuana has at least one benefit compared to 17% who believe that it has no benefits. Roughly two-thirds believe cannabis can help with pain management, while nearly half of all respondents believe it can help with epilepsy and multiple sclerosis (48%) and anxiety, stress, and depression (47%).

What's interesting about this particular find is that it comes shortly after the U.S. Food and Drug Administration (FDA) approved GW Pharmaceuticals' (NASDAQ:GWPH) Epidiolex as a treatment for two rare types of childhood-onset epilepsy known as Dravet syndrome and Lennox-Gastaut syndrome. GW Pharmaceuticals' lead drug is cannabidiol (CBD)-based -- CBD is the non-psychoactive component of the cannabis plant best known for its perceived medical benefits -- meaning it became the first cannabis-derived drug to gain approval from the FDA.

A researcher in a white lab coat making notes on his clipboard in the middle of a hemp farm.

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Then again, there are risks involved

However, cannabis isn't without risks. The study also shows that 91% of U.S. adults believe marijuana has at least one risk, which is 10 percentage points higher than the number who felt it had at least one benefit. The three most commonly identified risks of cannabis use were legal problems (51.8%), addiction (50%), and impaired memory (42%).

Furthermore, only a small percentage of respondents believe that secondhand marijuana smoke is somewhat or completely safe for adults (18%) and somewhat or completely safe for children (7.6%). Percentages this low suggest skepticism or concern among the public regarding cannabis use.

What's perhaps most notable about the findings is what the researchers behind the study had to say. In particular, they cautioned that many of the benefits cited by respondents have yet to be substantiated with clinical evidence.

With the exception of GW Pharmaceuticals' lead drug treating epilepsy and the EU approving GW's Sativex as a treatment for spasticity associated with multiple sclerosis, there's little in the way of clinical evidence to suggest that cannabis does much from a medical perspective. And by "clinical evidence," I mean evidence that the FDA, the U.S. regulatory body for pharmaceutical products, will accept as valid. This means university studies, as an example, don't count. 

Researchers also suggest that the wording of the survey questions may have impacted the results. 

A judge's gavel next to dried cannabis buds.

Image source: Getty Images.

Just to make matters more challenging...

The simple solution would be for the federal government to allow for increased medical research into cannabis to establish a profile of the drugs' risks and benefits. Having this profile available would make it considerably easier for federal lawmakers to decide whether or not to reschedule or de-schedule cannabis.

During the tail-end of the Obama presidency, promises were made to expand the number of federally approved grow facilities from one (the University of Mississippi) to some number greater than one. The idea was that having more grow farms would remove the supply constraint that's held back researchers from running clinical studies involving weed.

Unfortunately, despite receiving more than two dozen grow applications, sitting Attorney General Jeff Sessions has yet to review or approve any of them. This continues to constrain cannabis supply for research purposes.

The industry also is being held back by federal red tape with regard to getting approval(s) from regulatory agencies before conducting studies.

In other words, despite its perceived benefits among the public, marijuana still is likely a long way away from having those benefits proved or disproved scientifically.

Sean Williams has no position in any of the stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy.