Sidney Morgenbesser, NYPD, and the Categorical Imperative

Morgenbesser was leaving a subway station in New York City and put his pipe in his mouth as he was ascending the steps. A police officer told him that there was no smoking on the subway. Morgenbesser pointed out that he was leaving the subway, not entering it, and hadn't lit up yet anyway. The cop again said that smoking was not allowed in the subway, and Morgenbesser repeated his comment. The cop said, "If I let you do it, I'd have to let everyone do it." Morgenbesser replied, "Who do you think you are, Kant?" The word "Kant" was mistaken for a vulgar epithet and Morgenbesser had to explain the situation at the police station