What is a zone defence, and what do I do if I see one?

Zone defence isn't allowed in junior domestic basketball. Each defender must guard a player (man-to-man), following them around the court.

A team is playing a zone if its defenders are guarding areas of the court instead of players for too long, for example a player standing in the key and not following anyone, or defenders who don't follow an attacker cutting through the key.

If you see it, at the next dead ball tell the defending coach calmly that it looks like a zone and their players need to pick up a player each. If it continues, tell the court controller or referee coach. They decide whether to warn the coach formally and, if it keeps happening, give the coach a technical foul.

Players helping a teammate for a moment, or a defender caught out of position, isn't a zone. Look for a pattern, not a single moment.