Fall back (mercy) rule
The fall back (mercy) rule is where, when a team is leading by 20 points or more (10 points or more in U10's), the leading team is required to fall back behind their three (3) point line following a successful shot attempt, or whenever the opposition team in-bounds the ball. No defence may be played until the ball is dribbled or passed across the centre line. The penalty for non-compliance is a violation called by the referee with possession going to the opposing team.
The mercy rule:
9.1 Games shall consist of two halves of twenty (20) minutes.