In American and Canadian gridiron football, pass interference (PI) is a penalty that occurs when a player interferes with an eligible receiver's ability to make a fair attempt to catch a forward pass. Pass interference may include tripping, pushing, pulling, or cutting in front of the receiver or pulling on the receiver's arms. It does not include catching or batting the ball before it reaches the receiver. Once the ball touches any defensive player or eligible offensive receiver the above rules no longer apply and the defender may tackle the receiver or attempt to prevent him from gaining control of the ball.