Our federal marijuana policy is increasingly out of step with both the values of American citizens and with state law. The result is a system of justice that is schizophrenic and at times appalling.

Though the federal government considers marijuana a Schedule I Controlled Substance and bans its use for medical purposes, a growing number of states feel differently. Today, 18 states and Washington, D.C., have legalized medical marijuana for people suffering from debilitating medical conditions like cancer, epilepsy, severe nausea, multiple sclerosis and chronic pain. And on Tuesday, Colorado and Washington State voted to legalize marijuana for adult use, regardless of medical condition. But these states cannot stop the federal government from enforcing its own laws.

And federal drug laws are unjustifiably extreme. Consider the case of Chris Williams, the subject of this Op-Doc video, who opened a marijuana grow house in Montana after the state legalized medical cannabis. Mr. Williams was eventually arrested by federal agents despite Montana’s medical marijuana law, and he may spend the rest of his life behind bars. While Jerry Sandusky got a 30-year minimum sentence for raping young boys, Mr. Williams is looking at a mandatory minimum of more than 80 years for marijuana charges and for possessing firearms during a drug-trafficking offense.

This outcome is sad, of course — Mr. Williams will not be free to raise his teenage son — but it is also morally repugnant. Even if you think that the benefits of legalized medical marijuana do not outweigh the costs — a crucial debate, but one we can table for the moment — a coherent system of justice must explain why one defendant is punished more harshly than the next. It must explain why a farmer who grows marijuana in compliance with state law should be punished much more harshly than some pedophiles and killers. If we cannot explain this disparity, we should fight to change it.