"It was not until 1951, when Congress again took up the issue, that a reputable researcher was called to testify. Dr. Harris Isbell, director of research at the Public Health Service Hospital in Lexington, Ky., disputed the insanity, crime and addiction theories, telling Congress that 'smoking marijuana has no unpleasant aftereffects, no dependence is developed on the drug, and the practice can easily be stopped at any time.'

"Despite Dr. Isbell’s testimony, Congress ratcheted up penalties on users. The states followed the federal example; Louisiana, for instance, created sentences ranging from five to 99 years, without parole or probation, for sale, possession or administration of narcotic drugs. The rationale was not that marijuana itself was addictive — that argument was suddenly relinquished — but that it was a 'steppingstone' to heroin addiction. This passed largely without comment at the time.

"The country accepted a senselessly punitive approach to sentencing as long as minorities and the poor paid the price. But, by the late 1960s, weed had been taken up by white college students from the middle and upper classes. Seeing white lives ruined by marijuana laws altered public attitudes about harsh sentencing, and, in 1972, the National Commission on Marihuana and Drug Abuse released a report challenging the approach."