Raise taxes on pot, heroin, cocaine, methamphetamines...

What happened in 1930 that suddenly gave the repeal movement political muscle? The answer is the Great Depression and the ravages that it inflicted on federal income-tax revenues.

Prior to the creation in 1913 of the national income tax, about a third of Uncle Sam's annual revenue came from liquor taxes. (The bulk of Uncle Sam's revenues came from customs duties.) Not so after 1913. Especially after the income tax surprised politicians during World War I with its incredible ability to rake in tax revenue, the importance of liquor taxation fell precipitously.

By 1920, the income tax supplied two-thirds of Uncle Sam's revenues and nine times more revenue than was then supplied by liquor taxes and customs duties combined. ...

Before the income tax, Congress effectively ignored such calls because to prohibit alcohol sales then would have hit Congress hard in the place it guards most zealously: its purse. But once a new and much more intoxicating source of revenue was discovered, the cost to politicians of pandering to the puritans and other anti-liquor lobbies dramatically fell...

From 1930 to 1931, income-tax revenues fell by 15 percent.

In 1932 they fell another 37 percent; 1932 income-tax revenues were 46 percent lower than just two years earlier. And by 1933 they were fully 60 percent lower than in 1930.

With no end of the Depression in sight, Washington got anxious for a substitute source of revenue.

That source was liquor sales....

So, if the history of alcohol prohibition is a guide, drug prohibition will not end merely because there are many sound, sensible and humane reasons to end it. Instead, it will end only if and when Congress gets desperate for another revenue source.