Can a player override a call, and what happens?

Question

Accepted Answer

A player may override an official's line call, their partner's call, their own call, or any "in" ruling when the override favours the opponent.

Override of an official's "out" call that favoured the player: the rally is replayed, unless the player concedes the rally to their opponent.
Override of an official's "in" ruling that favoured the player: the opponent wins the rally.
Player line calls are otherwise not valid when line judges are used, except for the service court centreline and overrides in the opponent's favour.