Perpetual check

In the game of chess, perpetual check is a situation in which one player can force a draw by an unending series of checks. Such a situation typically arises when the player who is checking cannot deliver checkmate, while failing to continue the series of checks gives the opponent at least a chance to win. A draw by perpetual check is no longer one of the rules of chess. However, such a situation will eventually result in a draw by either threefold repetition or the fifty-move rule, but usually players agree to a draw (Burgess 2000:478).