I had this happen to me while being the Referee of a tournament game this past weekend. It was the second half (about 15 minutes remaining in the match) and I was sprinting across the field on a fast play and I got a cramp in my calf. At first it slowed me quite a bit and I hobbled around for about 45 seconds and was able to work it out without stopping the game.
So, my question is what would be the appropriate action to take if the Referee becomes unable to finish the match? Do one of the AR’s take over or is the match called if it is in the 2nd half?
USSF answer (March 24, 2009):
Unless the rules of the competition specify otherwise, the senior assistant referee (AR) takes over if the referee is unable to complete the match.
If there is no competent person to assume the duties of the senior AR, the new referee and the junior AR work the game alone. However, there is no change in authority; the referee remains in full control. The referee works one side of the field, the AR the other, but only the referee is permitted to use a whistle and retains all duties and powers granted by Law 5.