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So say my queen is pinned in front of my king by the opponents rook. However if I move my queen to check their king it is certain checkmate, is that legal? I'm not sure because I'm intentionally endangering my king to be taken on the next move, but technically there won't be a next move since I checkmate my opponent.

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    No, it would be an illegal move to leave your king in check. Commented Oct 1, 2016 at 22:39
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    This question comes down to "can I claim an illegal move (the mating move), even if the game 'is' over (by checkmate)?" And to be honest: yes, you can. Otherwise you could just move any pieces to a checkmate position and declare the game as a win - pretty pointless. Although it's not unheard of in blitz games. :)
    – Eiko
    Commented Oct 2, 2016 at 18:45
  • A related question (about the chess variant created by amending this rule): chess.stackexchange.com/questions/1515/… Commented Oct 5, 2016 at 13:07
  • I think OP's "move my queen" means "move my queen off the pin line". No chess piece can pin a queen; at most a rook can line-pin it, and that queen may move along the pin-line. For example white's line-pinned queen may play Qb6# here: wKb1, Qb2, Bc8, Pc5, bKa6, Rb7.
    – Rosie F
    Commented Sep 25, 2020 at 10:11

5 Answers 5

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Think of it this way:

Check mate is where nothing the opponent can do will save them from having you take their king on the next turn, so even if by putting their king in checkmate, you expose your own king, they can take your king before you can take theirs.

There is NO circumstance in which your actions put your own king into check without an opponent making a move.

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    One could argue that this answer were slightly, technically incorrect but, in spirit, this is just the right answer. This is the way to think about it. However, once one has learned to think of it roughly this way, one should read the other answers to understand the techincalities, because those are important, too.
    – thb
    Commented Jun 6, 2018 at 19:33
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The rules are clear. A move that puts your king in check is an illegal move (I'll leave it to you to find the reference; you might find the other rules helpful to review once you get there).

You cannot checkmate your opponent's king (or accomplish anything else) with an illegal move. Once you make an illegal move on the board, the following things happen:

  1. The position is restored to the position in effect before the illegal move is made.
  2. You get penalized for an illegal move. For the 1st and 2nd offenses, this results in your opponent's being awarded an extra 2 minutes on his clock. For the 3rd offense, the normal penalty is forfeit of the game.

Nice try, though.

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  • Currently the game is forfeited after the second offense, in rapid and blitz after first offense. Also in rapid and blitz games the position is not restored if the illegal move is not claimed immediately (although the players are allowed to agree to restore it). In the new laws for next year it is proposed that an illegal move is retracted only within the last 10 moves. Commented Oct 2, 2016 at 19:46
  • @IAPetrHarasimovic Thanks for clarifying about the FIDE Laws of Chess. In the USCF Rules, the tournament director has discretion regarding the 10-move limit if a king was in check and a move was made that left it in that state. In this situation, each move that does not address the check is illegal, and the 10-move counter keeps getting reset as the score moves are reversed. So, if the illegal king-still-in-check condition occurred 20 moves ago, the TD can direct that the position be restored either to the position when the king was first in check, or any intermediate position.
    – jaxter
    Commented Oct 7, 2016 at 6:14
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Basically if you are confused about pin/checkmate rule, just play the game out until one king is captured.

You move you Q to threat taking his king in your NEXT move. Unfortunately it's now his move and he takes your K first.

On the other hand, if you use your other piece to attack so that his K has to move into your pinned Q's firing range, you can capture (not threat to capture) his K with your Q before he can capture your K. Or in standard chess rule, he is checkmated.

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    In USCF Rules, the king may be captured in blitz, but not in a standard game, when it would be an illegal move and penalized. So, your comment should be interpreted to mean, "imagine playing the game out until...".
    – jaxter
    Commented Oct 7, 2016 at 6:19
  • An alternative way of looking at things would be to say that capturing an opponent's king would be a winning move but no player can be compelled to allow the king to be captured. Except at blitz, a player whose opponent blunders so as to allow capture of the king would be required to let the opponent substitute a different move, and a player who puts his opponent into a position where there are no moves that don't put the king in check would be required to offer a draw (the opponent would have to either accept the draw or forfeit).
    – supercat
    Commented Jun 8, 2018 at 20:58
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Official chess rules by FIDE
Rule 3.9 is as follows:

3.9 The king is said to be 'in check' if it is attacked by one or more of the opponent's pieces, even if such pieces are constrained from moving to that square because they would then leave or place their own king in check. No piece can be moved that will either expose the king of the same colour to check or leave that king in check.

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In standard chess, no, you cannot move into, nor make a move that puts your king in, check.

I noticed this is tagged chess-variants, so I will add that the rules for speed/blitz chess may be slightly different, in terms of penalties. In addition, in casual blitz games, that may be acceptable.

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  • Yes, in blitz games usually the player making an illegal move instantly loses the game (well, if claimed).
    – Eiko
    Commented Oct 3, 2016 at 9:26

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