The defending champions, GM Gata Kamsky & GM Irina Krush
The following regulations shall be in effect throughout the 2015 U.S. Championship and 2015 U.S. Women's Championship
- Prompt Arrival: Players are expected to arrive promptly for their games. Players more than 30 (thirty) minutes late for a round shall forfeit that round.
- Early Draws: A 30-move draw rule will be in effect throughout the Event, including any playoff games. Players may not agree to a draw in less than 30 moves.
- Electronic Devices: No cell phones or other electronic devices shall be allowed in the tournament area. Any violation involving a cell phone or other electronic device that emits any noise during a game shall result in forfeiture of that game.
- Time Control: 90 minutes for the first 40 moves followed by 30 minutes for the rest of the game with an addition of 30 seconds (increment) per move starting from move one.
- Notation: Due to the 30-second increment, Players are required to maintain an accurate and legible score sheet at all times during all games, and are required to keep their notation up-to-date.
- Chief Arbiter Discretion: In the event of an unexpected occurrence, the Chief Arbiter reserves the right to make all decisions in conjunction with or on behalf of the CHESS CLUB. Where not otherwise specificed, the 2015 U.S. Championship and 2015 U.S. Women's Championship shall both be governed by the FIDE Laws of Chess.
- Playoff Procedures: If two or more Players are tied for 1st, a playoff will be held. For the purposes of pairing players in the following scenarios, the following mathematical tie-breaks will be used: 1. Direct Encounter (if applicable), 2. Most Blacks, 3. Koya System, 4. Sonneborn-Berger, 5. Won Games. If there is no need for a playoff, then these tie-breaks will also be used for the purposes of the crosstable and any special prizes or trophies.
An Armageddon Game is defined as a game with base time of 45 minutes for each Player. Black will have draw odds. Each Player shall bid an amount of time (minutes and seconds, a number equal to or less than 45:00) with which they are willing to play in order to choose their color. The Player who bids the lowest amount of time chooses his color and begins with that amount of time; the other Player receives 45:00. If both Players bid exactly the same amount of time, the Chief Arbiter will flip a coin to determine who shall choose their color.
Two Players: The tie will be broken with a two-game rapid match (G/25+5). If the contest is still undecided, the match will be decided by an Armageddon Game.
Three players: If there are three Players tied for first, the two Players with the lowest tie-breaks will contest an Armageddon Game. The winner of this game will face the player with the highest tie-breaks as described above ("Two Players").
Four Players: Tie-breaks will be used to determine pairing numbers: 1 plays 4 and 2 plays 3. Each Player will contest an Armageddon Game. The winner of each game will face one another as described above ("Two Players").
More Than Four Players: If more than four players are tied for first place, a combination of math tie-breaks and playoffs will be used to find the top four players and the procedure described above ("Four Players") shall be followed. The format if more than four players are tied for first will be determined by the Arbiter and the Chess Club and Scholastic Center of Saint Louis.