Ryan Grim has just published This is Your Country on Drugs, and he has presented some of his main ideas at Huffpo.

[O]ur nation diverges sharply from the rest of the world in a few crucial ways. Americans work hard: 135 hours a year more than the average Briton, 240 hours more than the typical French worker, and 370 hours–that’s nine weeks–more than the average German. We also play hard. A global survey released in 2008 found that Americans are more than twice as likely to smoke pot as Europeans. Forty-two percent of Americans had puffed at one point; percentages for citizens of various European nations were all under 20. We’re also four times as likely to have done coke as Spaniards and roughly ten times more likely than the rest of Europe.

What is driving law enforcement regarding drug use.  Grim’s answer focuses on our ambivalence toward pleasure:

When pleasure is suspected, American drug use gets tricky, particularly when that high might do some real good, as in the case of medical marijuana.