Chop block (gridiron football)

In gridiron football, a chop block is an attempt by an offensive player to cut block a defensive player who is already being blocked by another offensive player. The second block may need to be below the thigh or knee, depending on the code. In the NFL, NCAA, and in high school football, the penalty for a violation is 15 yards.

Chop blocks are banned because they are dangerous. They were first banned in the NCAA in 1980.