One of the most important lessons I learned in law school concerned how to win an argument. And regardless of whether the argument is made in a court of law or in the court of public opinion, one timeless principle will always apply: whereas amateurs try to direct an argument’s logic, professionals work to control its terms – while true masters of the art take the principle one step further and control its underlying facts.

To see a brilliant example, look no further than some of the greatest masters of this art: the public relations professionals who work for the tobacco industry. In the 1950s and 60s, when the earliest research about the deadly harms of tobacco began to come to light, the industry’s PR machine transformed the terms of the national discourse (“More doctors smoke CAMELS than any other brand of cigarette!”); but quickly, as the evidence kept mounting, the industry had to step up their game and seize control of the facts. That’s why they began sponsoring their own research, then began promoting their contrary findings to establish that there was a “debate” among the medical community as to whether smoking tobacco caused health problems.

The strategy worked brilliantly, and the industry was able to go on profiting off the deaths of half a million Americans per year without anyone going to jail.

It may seem odd to open a discussion of the significance of a federal hearing on cannabis with a story from the tobacco industry, but I thought that a little context was required to appreciate the three days of federal hearings on the constitutionality of cannabis’ continuing Schedule I classification beginning today in Sacramento, California – and to understand why these historic hearings are a very, very big deal.

“This is Where the Light Is.”

A man walking home from work late at night happened upon an unusual sight: another man, looking somewhat disheveled, scouring on his hands and knees the narrow circle of light thrown down onto the sidewalk by a street lamp above. There was obviously nothing there but concrete and dirt, so the man asked the other what he was so fervently seeking.

“My keys,” came the reply.

“One glance can show you they’re not here,” said the bewildered man. “Why don’t you try searching somewhere else?”

“Because,” said the other, resting on his knees. “This is where the light is.”

The story in the joke sounds absurd, but in a very real sense, this is how courts of law operate in the United States. With only one, very narrow exception to the rule (look up “judicial notice” if you’re feeling extra wonky), courts weighing the outcome of a case are not permitted to even look at any facts except those in the established evidentiary record of that case – in other words, where the light is.

While the rule sounds impossibly esoteric, its application has very real consequences. So, for example, when the Supreme Court decided in 2013 to finally terminate a petition to reschedule cannabis, it did so only with the benefit of evidence gathered in two separate hearings – one conducted in 2002 and the other all the way back in 1986. Thus, even though a huge amount of research on the medical efficacy of cannabis had been published in the decade before the Court made their decision, they were not allowed to consider it at all when making their decision. That’s not where the light is.

That’s why today’s hearing is a very big deal. By finally taking updated testimony from eminent experts – including Dr. Carl Hart, Dr. Phillip Denny, and the Leaf’s co-founder Chris Conrad – the federal court system will permit itself to know what almost every American already knows: that the Schedule I classification of cannabis is bogus. And those facts will be binding for the entire duration of an appeal, even it if goes (as it likely will) all the way back to the Supreme Court.

Schedule I classification requires, by the way, a rational and scientific determination that a drug lacks any currently accepted medical value in the US; that it also has a high potential for abuse; and that there is no safe way to administer it, even under a doctor’s supervision. This rational determination is required to be made, according to the language of the Controlled Substances Act which established the schedules, both intrinsically and comparatively, meaning that each drug must be evaluated not only on its own merits but also in comparison to drugs in the same schedule as well as other schedules.

Thus the government’s expert witness, Dr. Bertha Madras, has the unenviable job of explaining (under cross-examination) why cannabis belongs in the same category as heroin, but that cocaine (Schedule II) and crystal meth (Schedule III) should be less restricted. (In 2012, DEA Administrator Michele Leonhart stumbled badly when trying to make a similar case before Congress.) And if Judge Kimberly Mueller finds that there is no rational basis for the continued scheduling of cannabis according to these metrics, she will strike down the classification as unconstitutional.

To be sure, such a move will certainly provoke an appeal; but the damage will have been done because the facts will have already been established. All later appeals courts will be bound by the same factual findings that cannabis doesn’t belong in Schedule I — because that’s where the light will be.