Once upon a time, a musician needed one of these in order to work in a New York City establishment that served alcohol. It is, in part, a relic of an earlier version of the War on Drugs - if you had a drug bust on your criminal record, you lost your card, and thus your keys to Mecca. The two most famous victims: Billie Holiday, for a late-1940s drug conviction, and Thelonious Monk, busted in 1951 when his car was pulled over by police, who stumbled upon Bud Powell's cannabis.