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Chess rule for claiming a draw
The fifty move rule in chess states that a player can claim a draw if no has been made and no pawn has been moved in the last fifty moves (for this purpose a "move" consists of a player completing a turn followed by the opponent completing a turn). The purpose of this rule is to prevent a player with no chance of winning from obstinately continuing to play indefinitely or seeking to win by tiring the opponent. Chess positions with only a few pieces can be "solved", that is, the outcome of best play for both sides can be determined by exhaustive analysis; if the outcome is a win for one side or the other (rather than a draw), it is of interest to know whether the defending side can hold out long enough to invoke the fifty move rule. The simplest common endings, called the basic checkmates, such as king and queen versus king, can all be won in well under 50 moves. However, in the 20th century it was discovered that certain endgame positions are winnable but require more than 50 moves (without a capture or a pawn move). The rule was therefore changed to allow certain exceptions in which 100 moves were allowed with particular material combinations. However, winnable positions that required even more moves were later discovered, and in 1992, FIDE abolished all such exceptions and reinstated the strict 50 move rule over the board. In correspondence chess, a rule similar to these endgame exceptions still applies, in that a player can claim a win or draw based on seven piece endgame tablebases (which do not consider the 50 move rule).

If seventy five moves are made without a pawn move or capture being made, the game is drawn unless the seventy fifth move delivers a checkmate. No claim needs to be made by either player, as the draw is mandatorily applied by the arbiter. refn|Article 9.6.2 in Fide Laws of Chess between Jan Timman and Christopher Lutz, an endgame with a rook and bishop versus a rook occurred. White is striving for the winning Philidor position while Black is employing the drawing Cochrane Defense and the "second rank defense" (see rook and bishop versus rook endgame). Black was defending well in the difficult defense and could have claimed a draw on the 119th move. Lutz notes that he claimed a draw on move 121, ironically making a move that enters what would have been a losing position.

A draw by the fifty move rule could have been claimed after Black's 112th move in a 1991 game between Anatoly Karpov and Garry Kasparov, but neither player claimed it. The last capture occurred on White's 63rd move (and the last pawn move occurred before that). White could have written his 113th move (which wouldn't have been a capture or pawn move) on his scoresheet and claimed a draw. refn|Rule 9.3.1 in FIDE Laws of Chess If 115. Ke8, then 115 Rxf5 116. Nxf5, and the position is clearly drawn because the two knights cannot force checkmate (see two knights endgame).

An unusual event occurred in a game in the 2001 Armenian Championship between Smbat Lputian (who won the championship) and Gevorg Haroutjunian. The last pawn move was on White's 86th move and no captures occurred after it. (The game was a theoretical draw from before here until Black's 141st move.) Black could have claimed a draw after White's 136th move (or at any of the subsequent moves). Instead, the game continued and Black resigned on his 142nd move after White had achieved a forced winning position even though the right to claim a draw was still in effect.

Another unusual event occurred in the Aeroflot Open of 2008 in a game between Nguyễn Ngọc Trường Sơn and Maxime Vachier Lagrave. The last capture was on White's 71st move, creating a rook and bishop versus rook endgame. The game was a theoretical draw until Black blundered on his 113th move. White managed to find the win, but could not secure checkmate or the win of the black rook before the fifty move rule came into effect, and Black claimed a draw.