Rule 723.5b

The controller of another player can’t make choices or decisions for that player that aren’t called for by the rules or by any objects. The controller also can’t make any choices or decisions for the player that would be called for by the tournament rules. Example: The player who’s being controlled still decides if they will leave to visit the restroom, trade a card to someone else, agree to an intentional draw, or call a judge about an error or infraction.