Pat Venditte is a switch pitcher, capable of pitching proficiently with both arms. He is recognized as the only active professional pitcher who is able to do this.
Venditte's rare ambidextrous abilities prompted the MLB to adopt a new rule for dealing with ambidextrous pitchers, known colloquially as the "Pat Venditte Rule". This rule essentially requires any ambidextrous pitcher to declare which hand he will use to pitch to a batter before the at-bat starts, and to throw with that hand through the entire at-bat.
Source:
Dan Formosa & Paul Hamburger, Baseball Field Guide (New York: The Experiment Publishing, 2016) 72–73
