Question: What are the reasons a player’s hand could be declared dead?

Answer:  These are the most common reasons a player’s hand can be declared dead:

• A player makes an incorrect exposure
• A player exposes tiles and it is obvious that based on the exposures there is no viable hand on the card.
• A player exposes tiles and it is obvious that a single tile or pair is needed and based on what has been discarded or has been exposed, the hand cannot be completed.
• A player exposes tiles for a concealed hand.
• A player has too few tiles (example discarding before picking a wall tile) or too many tiles in or on their rack.
• A player picks out of turn.
• A player picks up a misnamed tile causing an erroneous exposure.
• A player picks and racks from the wrong wall that has been pushed out.
• A player does a Joker exchange before picking their tile from the wall.
• A player declares Mah Jongg in error (see also ID123)

Source:  Mah Jongg Made Easy 2020 pages 16, 17, 19, 20, & 21