The second big problem with the drug war is that it has exacerbated poverty and devastated the family structure of African-Americans. Partly that’s because drug laws are enforced inequitably. Black and Latino men are much more likely than whites to be stopped and searched and, when drugs are found, prosecuted.

Here in Los Angeles, blacks are arrested for marijuana possession at seven times the rate whites are, according to a study by the Drug Policy Alliance, which favors legalization. Yet surveys consistently find that young whites use marijuana at higher rates than young blacks.

Partly because of drug laws, a black man now has a one-in-three chance of serving time in prison at some point in his life, according to the Sentencing Project, a group that seeks reform in the criminal justice system. This makes it more difficult for black men to find jobs, more difficult for black women to find suitable husbands, and less common for black children to grow up in stable families with black male role models. So, sure, drugs have devastated black communities  but the remedy of criminal sentencing has made the situation worse.

The third problem with our drug policy is that it creates crime and empowers gangs. “The only groups that benefit from continuing to keep marijuana illegal are the violent gangs and cartels that control its distribution and reap immense profits from it through the black market,” a group of current and former police officers, judges and prosecutors wrote last month in an open letter to voters in California.

I have no illusions about drugs. One of my childhood friends in Yamhill, Ore., pretty much squandered his life by dabbling with marijuana in ninth grade and then moving on to stronger stuff. And yes, there’s some risk that legalization would make such dabbling more common. But that hasn’t been a significant problem in Portugal, which decriminalized drug use in 2001.

Likewise, medical marijuana laws approved in 1996 have in effect made pot accessible to any adult in California, without any large increase in usage. Special medical clinics abound where for about $45 you can see a doctor who is certain to give you the medical recommendation that you need to buy marijuana. Then you can visit Mr. Kim and choose one of his 31 varieties, topping out at a private “OG” brand that costs $75 for one-eighth of an ounce. “It’s like a fine wine, cured, aged, dried,” he boasted.

Or browse the online offerings. One store advertises: “refer a friend, get free joint.” And the world hasn’t ended.

One advantage of our federal system is that when we have a failed policy, we can grope for improvements by experimenting at the state level. I hope California will lead the way on Tuesday by legalizing marijuana.