Explained: Why Jonny Bairstow was ruled out in pivotal Ashes moment

The incident occurred in the 52nd over of the England innings with Bairstow and Ben Stokes rebuilding for England after the dismissal of Ben Duckett.

Bairstow left the final ball of Cameron Green's over alone to the wicket-keeper and started walking outside the crease assuming the ball was dead. However, an alert Carey realised there was an opportunity to dismiss the batter and effected a direct hit at the striker's end to catch Bairstow well short of his ground.

In what could be a defining moment in the series, Bairstow was left fuming as the Aussies celebrated around him.

According to law 20.1.2 of the MCC's Laws of Cricket, "the ball shall be considered to be dead when it is clear to the bowler’s end umpire that the fielding side and both batters at the wicket have ceased to regard it as in play."

Carey, having watched Bairstow make it a habit of walking outside the crease early, used the chance to throw down the stumps and find the England right-hander out of his ground.

In this case, the fielding side clearly considered the ball to still be in play and hence it wasn't a dead ball.

The dismissal left England's skipper with Stuart Broad and the rest of the tail with 178 runs to chase down.