"It was scientifically without merit because when you drink, it goes through your stomach," Peck said. "Otherwise, most of us would be lobotomized."
That's not to say there aren't substantial health detriments to alcohol and marijuana use.
Both can have impacts on brain development in younger users. Smoking marijuana can cause respiratory issues. Long-term alcohol consumption is linked with a host of cardiovascular and nervous system problems, not to mention cirrhosis. And that's the short list.
But just like opponents have overplayed the drugs' detrimental effects, advocates have exaggerated their benefits.
Think "medicinal." In 2010, ahead of California's failed marijuana-legalization referendum, several medicinal marijuana users shared their symptoms and ailments.
Among them were AIDS patients who needed it to boost their appetites. The husband of a cervical cancer sufferer recalled how cream-based marijuana soups eased his wife's agony more effectively than the powerful painkiller Dilaudid.
Others, however, told CNN of lesser maladies. One said with a smirk that he'd jammed his thumb. Another said he'd been stressed out at work and explained how less-reputable dispensaries had doctors in back rooms who prescribed pot for almost anything.
It was no different when alcohol was banned, Peck said. Despite the American Medical Association saying alcohol had no medicinal value, the Volstead Act, which led to the federal ban on alcohol, stated that no one could prescribe alcohol except "a physician duly licensed to practice medicine" -- much to the delight of the nation's Jay Gatsbys.
"Yes, medicinal whisky -- all of a sudden, all of these doctors are saying we need to prescribe this because there's so much money to be made. You could prescribe a pint a week," Peck said. "We know enough about alcohol now; it's not medicinal."
As Prohibition expert Daniel Okrent wrote in 2010, "... all too often, 'medicinal' has been a cynical euphemism for 'available.' "
John Kane, a U.S. district judge in Colorado, explained that while there was a medical exception to Alcohol Prohibition, health had little to do with its repeal.
No one was clamoring to make brandy legal to cure the country's headaches, explained Kane, whose father was a pharmacist during Prohibition and prescribed brandy to his patients.
Rather, the nation had grown weary of the organized crime that accompanied Prohibition, he said.
Many of the immigrant groups vilified by the teetotalers formed the organized crime units that plagued Prohibition days, he said. Prior to the ban on alcohol, gangs generally ran numbers, extorted folks or charged fees for protecting neighborhoods.
"Then Prohibition came along, and that basically gave them an American Express black card," he said. "It subsidized criminal activity in this country."
The price of legalization
Just as Prohibition bore Al Capones and strengthened the Frank Costellos and "Lucky" Lucianos, American drug prohibition has spawned a host of cartels south of its border. They wage war against each other for the rights to the most lucrative illegal drug market on Earth -- the United States -- which by some estimates, consumes two-thirds of all the illegal drugs in the world.
Yet there is a major difference between Capone's henchmen and the Mexican cartels: "The violence is not to the scale of what's going on in Mexico," Peck said.
The St. Valentine's Day Massacre of 1929, one of the most heinous crimes of the era, left seven dead. That many could be murdered in a Mexican border town on your average Wednesday.
How big a hit the cartels would take if the United States legalized pot is a matter of debate, and conclusions vary widely. While U.S. officials said in 2009 that 60% of cartel revenue came from weed, the RAND Corporation said the following year that "15-26 percent is a more credible range."