The folks trying to lock up pot smokers aren't the prestigious public health professionals, professors, prosecutors, and defense attorneys who have banded together to submit what appears to be enough signatures to put the country's most sweeping marijuana initiative on the Washington State ballot. No, the people holding a rally today in Olympia to oppose Initiative 502—which would legalize and regulate pot for all adults—are medical marijuana patients, attorneys who specialize in marijuana defense, and activists who want legalization with fewer regulatory controls. They complain that too many people would get busted for DUIs while driving with active (not inactive) THC in their system. Of course, maintaining the status quo isn't a big deal for them if I-502 fails. A lot of them make money running pot dispensaries, and many lawyers make their living defending marijuana cases. The folks braying loudest against I-502 are also the same people (Douglas Hiatt, Jeffrey Steinborn, and Vivian McPeak) who ran previous initiative campaigns to legalize marijuana and failed to make the ballot. Maybe they're feeling butthurt that someone else is doing a better job. They've all done commendable work in the past, but now they are at the vanguard of a misguided campaign to lock up pot smokers. If they succeed in stopping I-502, perhaps there will be a handful more DUI arrests for pot under the imperfect initiative, because the science is admittedly unclear. But here's one thing that is absolutely clear: Law enforcement in Washington will continue to arrest about 13,000 people for pot every year unless we pass I-502. Those people who are busted will be disproportionately racial minorities. And about 90 percent of those people will be arrested for simple possession—not growing or selling—and face up to 90 days in jail, exorbitant legal bills, and a criminal record.

If I-502 passes, the threshold for establishing probable cause would remain as high as it is today: We're not seeing people pulled over much for pot DUIs now; that wouldn't change. Past campaigns in other states to legalize marijuana have failed because they were attacked for lacking strong DUI provisions. So it's a matter of picking our preference. Which is worse? Racking up another 13,000 arrests each year or the mere possibility of a smattering of DUIs for people with active THC in their system? It seems silly to make the perfect the enemy of the good when so many arrests are at stake, because we're never going to get perfect system for buying and selling drugs. Just look at liquor laws. They're flawed, too, but we ended prohibition.