Here are just three of the rules in the British Crown Green Bowls Association (BCGBA) Laws of the Game.
6. Running Jack or Bowl:
6.1. A bowl played while the jack or preceding bowl is in motion shall be forfeited.
6.2. If a running jack or bowl appears to be in danger of striking a still bowl or jack belonging to another end, such running jack or bowl should be stopped and returned to be replayed
6.3. If a running bowl is impeded in any way, except by either player, it must be played again. If a running bowl is impeded by either player, all the offender(s) bowls shall be forfeited at that end.

