A push in the back (colloquially "in the back") is a free kick awarded in Australian rules football against a player who illegally tackles or interferes with a player from behind when contesting possession.
Due to the lack of an offside rule, with the exception of when a free kick or mark is paid players can be challenged from any direction at any time not always with full awareness of their opponent's positioning, potentially disadvantaging those playing in front whole sole intention is gaining possession.
The rule is applied in two different circumstances: when the ball carrier is tackled and marking contests.
While it was widely introduced in 1897, the rule is as almost old as the sport with its necessity to ensure the safety of players having been debated since 1860.[1][2]