According to Harrah's WSOP Rules:

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38. Penalties: A penalty MAY be invoked if a player exposes any card with action pending, if a card(s) goes off the table, if soft-play occurs, or similar incidents take place. Penalties WILL be invoked in cases of abuse, disruptive behavior, or similar incidents. All penalties will be issued in Harrah’s sole discretion.

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66. A player who exposes his or her cards during the play may incur a penalty, but will not have his or her hand killed.

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