En Passant - Threefold Repetition and Stalemate

Threefold Repetition and Stalemate

The possibility of an en passant capture has an effect on claiming a draw by threefold repetition. Two positions whose pieces are all on the same squares, with the same player to move, are considered different if there was an opportunity to make an en passant capture in the first position, because that opportunity by definition no longer exists the second time the same configuration of pieces occurs (Schiller 2003:27).

In his book about chess organization and rules, International Arbiter Kenneth Harkness wrote that it is frequently asked if an en passant capture must be made if it is the only move to get out of stalemate (Harkness 1967:49). This point was debated in the 19th century, with some arguing that the right to make an en passant capture is a "privilege" that one cannot be compelled to exercise. In his 1860 book Chess Praxis, Howard Staunton wrote that the en passant capture is mandatory in that instance. The rules of chess were amended to make this clear (Winter 1999). Today, it is settled that the player must make that move (or resign). The same is true if an en passant capture is the only move to get out of check (Harkness 1967:49).