A now defunct rule in football which made it illegal to enter a "halo" that extended two yards around any player attempting to receive a punt. Entering the halo would result in the same penalty as punt catch interference. The rule was abolished in 2003, returning the rule to require contact with the returner for an interference flag to be thrown.
The halo violation was a rule change attempting to maximize player safety by establishing a protective halo around vulnerable return men. By creating a halo, the returner could field a punt without fear of a player racing down the field and applying a crushing hit while their attention was on the punt. Critics of the halo rule claimed it was too arbitrary, and made it too easy to throw a flag on a player if they were a hair too close to the returner. The rule was removed after large amounts of criticism, and the rule was restored to require contact with the player for a penalty to be assessed.