Sen. Arlen Specter's announcement that he is switching parties isn't his first time. Specter actually began his political career as a Democrat and switched to the Republicans in 1966 when running for district attorney in Philadelphia.
He wrote about it in a his autobiography, Passion for the Truth: "Changing parties involved a high level of trauma. It wasn't like changing religions, but there were elements of arguable disloyalty and opportunism that rubbed me the wrong way."