Some house rules hand must be shown but TDA rules do not. The WPT has had this for a while The WSOP I believe allowing this now. I know Jack Effel has always said player must show to win pot, but Matt Savage has said otherwise, if a player mucks the last person with a live hand wins the pot without having to show. Now this does not apply if you declare a hand but not turn over and your opponent mucks...
Interesting. Here's the complete relevant sections from the
TDA rules:
13: Tabling Cards & Killing Winning Hand
A: At showdown, a player should put all cards on the table so the dealer and players can read the hand clearly . “All cards” means both hole cards in holdem, all 4 hole cards in Omaha, all 7 cards in 7-stud, etc. Dealers cannot kill a hand that was tabled and obviously the winning hand.
B: If a player does not fully table his cards, then mucks thinking he has won, he does so at his own risk. If the cards are not 100% identifiable and the TD rules that the hand could not clearly be read, the player has no claim to the pot. The TDs decision on whether a hand was sufficiently tabled is final.
14: Live Cards at Showdown
A: If the house does not have a mucking line or forward motion rule at showdown, pushing non-tabled cards forward face down does not automatically kill them; a player may change his mind and table his cards if they remain 100% identifiable. However, the cards are at risk of being killed by the dealer when he pushes them into the muckpile.
B: If a mucking line or forward motion rule is in effect at showdown, house standards apply.
15: Face Up for All-ins.
All cards will be tabled without delay once a player is all-in and all betting action by all other players in the hand is complete. See Illustration Addendum.
16: Showdown Order.
In a non all-in showdown, if cards are not spontaneously tabled, the TD may enforce an order of show. The last aggressive player on the final betting round (final street) must table first. If there was no bet on the final street, then the player who would be first to act in a betting round must table first (i.e. first seat left of the button in flop games, high hand showing in stud, low hand showing in razz, etc.). Except where house policy requires a hand to be tabled during the order of show, a player may elect to muck his hand face down.
17: Playing the Board at Showdown
When playing the board a player must table all hole cards in order to get part of the pot.
18: Asking to See a Hand
Players not still in possession of their cards at showdown, or who have mucked face down without tabling their cards, lose any rights or privileges they may have to ask to see any hand.
Here's the thing though -this is the equivalent rule from the
2013 WSOP rules (emphasis added):
70 . Showdown: At the end of the last round of betting, the participant who made the last aggressive betting action in that betting round (last person to bet or raise on the final round of betting) must show first. If there was no bet in the last round, the participant to the left of the button shows first, and so on in a clockwise direction. In stud games, the participant with the high board must show first. In razz, the lowest board shows first. At showdown, any participant at the table may request to see a folded hand from any participant who has called all bets on the last round of betting. The winning hand must be shown to claim the pot. If a participant refuses to show their hand and intentionally mucks his or her hand, the participant in violation will receive a penalty, in accordance with Rules 39, 102 and 103.
Note that the highlighted section varies TDA rule 16, and directly contradicts TDA rule 18.
It's worth remembering that the TDA rules
only apply to tournaments where the house adopts them in full. The WSOP does
not adopt the TDA rules - it has its own full set of rules (some of which are based on / similar to the TDA rules).
Personally I don't like the TDA rules on this issue: Rule 18 in particular leaves a hole wide open for angle shooting and collusion. That aside though, I think the important thing to take away is this:
Unless you're
absolutely sure that the house rules where you're playing say otherwise, if a pot goes to showdown assume that you'll need to show all your cards in order to win any chips, and that
any player who was dealt in can ask to see the hand of any player involved in the showdown.