It appears that David Frum's piece for the very last print edition of Newsweek, "The Perils of Legalizing Pot," went to press before the magazine's fact checker(s) could take a pass at it (Update: sources tell me Newsweek has no fact checkers. That explains what follows below). 

In the second paragraph of his column, Frum writes, "Marijuana possession is now legal in Colorado and Washington. California also allows marijuana possession, if users can pay a doctor to prescribe it as 'medicine.'" Because marijuana is a Schedule I drug, doctors can't "prescribe" marijuana, they can only recommend it. 

While that error may seem semantic (it's not), the error Frum makes in the very next paragraph of his column is far more stark: "Even in the 47 states that formally ban marijuana, the drug is available everywhere and at modest cost." Eighteen states and the District of Columbia have legalized medical marijuana; Rhode Island decriminalized it this year, and other states and municipalities have done so in the past. Ergo, 47 states do not have formal bans on pot. 

As much (deserved) flack as Newsweek gets these days, I'm still surprised that the second error made it into print, as it contradicts Newsweek's own reporting on the subject. From an Oct. 22, 2012 story, titled "The New Pot Barons: Businessmen Bank on Marijuana": 

Twelve states now treat a personal stash like a minor traffic offense, 17 allow medical marijuana...

With November's passage of a medical marijuana ballot initiative in Massachusetts, the total is now 18.

David Frum didn't just insult the intelligence of his readers by failing to do even a smidgeon of research, he also insulted his colleague, Tony Dokoupil, who has done a lot of marijuana reporting this year. Most (but not all) of it has been sound enough to have served Frum's column. 

Take a look at some of the verifiable claims he simply guesses at: 

Although data are difficult to come by, it’s generally scientifically accepted that Americans smoke more marijuana per person than any other people on earth.

Data is not actually difficult to come by. From the 2012 U.N. World Drug Report

Overall, annual prevalence of cannabis use remained stable in 2010 (2.8-4.5 per cent of the adult population in 2009), the highest prevalence of cannabis use being reported in Oceania (essentially Australia and New Zealand) at 9.1-14.6 per cent, followed by North America (10.8 per cent), Western and Central Europe (7.0 per cent) and West and Central Africa (5.2-13.5 per cent). While the prevalence of cannabis use in Asia (1.0 - 3.4 per cent) remains lower than the global average, due to Asia's large population the absolute number of users in Asia, estimated between 26 million and 92 million, remains the highest worldwide.

More Frum:

If there’s one thing on which we can all agree, it is that legalization will mean even more use by even more people.

Again, research pertaining to this claim is available, for free. A 2011 study published in Addiction (and analyzed by Jacob Sullum) found that "the prevalence of cannabis use among Dutch citizens rose and fell as the number of coffeeshops increased and later declined, but only modestly." A study conducted by medical researchers at Brown University, meanwhile, found that "while marijuana use was common, there was no significant difference in rates of pot use between the years before and after legalization in Rhode Island."

Frum goes on to say that marijuana users have "have fewer friends and occupy lower rungs on the socioeconomic ladder." While I couldn't find any research indicating that pot smokers have fewer friends (or more), the success of pot smokers like Barack Obama, Bill Clinton, George W. Bush, Mitch Daniels, Peter Lewis, and many, many, many others suggests that it's possible to smoke pot and be successful. Upon reaching full volume, Frum does away with facts entirely: "Marijuana smoking is a sign of trouble, a warning to heed, a behavior to regret and deplore." 

He's entitled to his opinion, of course. But Newsweek should not have let him lie and distort research to bolster it.