JOKER EXCHANGE MISTAKE CAN BE CORRECTED (ARTICLE 224)

Commentary: When a player does a joker exchange, they are committed to follow through after the tiles have been exchanged. If there was a mistake, it can be corrected as long as the receiving player has not yet discarded to end their turn.

NOTE: The question from the player in the bulletin has a typo because the only hand that spans from 3-8 is a Singles-Pairs #5 and jokers can’t be used so it must have been a 6 crak. Shout-out to Dottie McCarthy Tieghe for calling attention to this!

Question from a player: Player B received an 8 crak during a joker exchange, though she called for a 3 crak. She realized the mistake. Player A who passed the 8 crak had a 3 crak in yer rack. Player B with the exposure had not yet discarded. Is Player A allowed to take back the 8 crak and give the correct 3 crak to Player B, so that a proper joker exchange can be made?

Answer from the league: If a player replaces a Joker with an incorrect tile leading to an incorrect exposure, and it is not noticed before a discard is made, then the player with the incorrect exposure is “dead.” If it is noticed before a discard is made, the error may be corrected with no penalty.

Source: Mah Jongg Made Easy (2024 page 24 #14)

Other answers from the NMJL: If a player replaces a Joker with an incorrect tile leading to an incorrect exposure, and it is not noticed before a discard is made, then the player with the incorrect exposure is “dead.” If it is noticed before a discard is made, the error may be corrected with no penalty.

Yes, the correct tile can be given to Player B, as long as [they] have not discarded yet.

Source for other answers: National Mah Jongg League Bulletin Q&A (2024 #10)