9.15 BALLS MOVING SPONTANEOUSLY - 5 SECOND RULE (8-BALL RULE)

A shooter's shot is considered completed after all balls have come to a final resting position. If, within five (5) seconds of all balls reaching their final resting position, a ball shifts, turns or otherwise moves by itself, the ball shall remain in the position it assumed and play continues.

A hanging ball that falls into a pocket by itself after being motionless for 5 seconds (or longer) shall remain pocketed and play will continue. If the hanging ball is the 8-ball or the cue ball, that ball should be replaced as near as possible to its original position immediately prior to the incident and play continues. 

NOTE: In regard to coaching leagues, no coaching is allowed once all balls come to rest and it is the incoming player's turn at the table.