ATTACKER HITS BEHIND (HIT OR KNOCK IN) (Rule 12).
In the case of any infringement or delay by the team facing the hit, a Penalty 5b shall penalty may be awarded.
For example, If the infringement is deliberate or is for coming onto the field of play from offside it should be a Penalty 5b but otherwise may be a Penalty 5a.
PENALTIES 2 and 3 (Rules 33, 34 and 38 and Annex B, paragraph 18).
If the team facing the hit infringes the rules, the umpire shall raise an arm and allow the penalty to be taken as normal; if a goal is scored or awarded (as per Rule 38a), play will be started with a throw in as normal from the centre unless the infringement is deliberate or dangerous in which case the umpires should blow the whistle to stop the clock and restart play with a Penalty 5b, teams having changed ends; if a goal was not scored or awarded then a Penalty 7a will be awarded (Penalty Retaken).