[This originally ran Feb. 19.]

Today’s post is brought to you by maryjane, Mexican locoweed, killer green bud, reefer and the number 420. I know almost nothing about marijuana other than many people smoke it, so this is a scholarly exercise.

Four states (Washington, Oregon, Colorado, Alaska) and the District of Columbia have legalized recreational use; none have imploded, although you could make a case for D.C. Some states allow medical use. But in broad swaths of the South and Midwest, lives are still ruined because of jail sentences for possessing even the smallest quantities of a plant that grows wild, a substance that wasn’t outlawed until the last Depression.

Why is weed illegal? (See, I’m a hipster, called it weed.)

British journalist Johann Hari found the answer while researching his book “Chasing The Scream: The First and Last Days of the War on Drugs.” He wrote recently for the HuffPost Politics blog: “In 1929, a man called Harry Anslinger was put in charge of the Department of Prohibition in Washington, D.C. But alcohol prohibition had been a disaster. Gangsters had taken over whole neighborhoods. Alcohol – controlled by criminals – had become even more poisonous. So alcohol prohibition finally ended – and Harry Anslinger was afraid. He found himself in charge of a huge government department, with nothing for it to do. Up until then, he had said that cannabis was not a problem.”

Mr. Anslinger wrote to 30 prominent scientists who studied the subject; 29 said cannabis presented no health risks. When he could trot out one “expert” to back him and cite a high-profile murder, he took his case to newspapers craving sensational lies. Parents were panicked; laws were passed.

When people pointed to prohibition and criticized the latest government overreach, they were told to shut up or else. Some things never change.