In the NFL, a defensive player commits a "roughing the kicker" foul if he (a) contacts the plant leg of the kicker while his kicking leg is still in the air; or (b) slides into or contacts the kicker when both of the kicker’s feet are on the ground. It is not a foul if the contact is not severe, or if the kicker returns both feet to the ground prior to the contact and falls over a defender who is on the ground.[2]
The penalty for such a violation in most leagues is 15 yards and an automatic first down. When such a violation occurs, the team about to surrender possession via a punt will retain its possession as a result. If the violation occurs when a successful field goal is kicked, the yardage is assessed on the ensuing kickoff, unless the offended team elects to accept the penalty and continue its drive in hopes of scoring a touchdown, which is referred to "taking the points off the board".[3]
Such protections are also extended to the holder during field goal kicks; the penalty for roughing the holder is identical.