When is the jack dead, and what happens next?

From laws 18 to 21 of the Laws of the Sport of Bowls (Crystal Mark 4th edition):

A jack moved by a bowl in play into the front ditch (within the side boundaries) is still live. Its position is marked with a white indicator.

The jack is dead if, after being moved by a bowl in play, it:

• passes completely outside the boundaries of the rink;
• comes to rest in a hollow in the face of the bank; or
• comes to rest less than 20 metres from the centre of the mat line (measured in a straight line to its nearest point).

It is not dead if it stops on top of a toucher in the ditch or on top of bowls within the rink. A jack that rebounds off the bank back onto the rink stays in play.

What happens: the end becomes a dead end. It doesn't count, and is replayed in the same direction (unless both skips agree otherwise), with the same player playing first. A Controlling Body may instead choose to re-spot the jack and play on. The skips (or singles opponents) decide whether the jack is dead; if they disagree, they call the umpire.