In a blitz game, when my king is checked, I make an illegal move that checkmated the opponent and pressed the clock. Then my opponent captured my king and claimed victory. Capturing the king is not a legal move. Who wins?

  • Related / duplicate: Is taking the opponent's king an illegal move?
    – Glorfindel
    Commented Feb 10, 2018 at 9:30
  • @Glorfindel This is not a duplicate of that question. That question asks if capturing the opponent's King is an illegal move and in this question the OP knows the answer to that question. This is not the question he asks. It is a very good question indeed. Commented Feb 10, 2018 at 11:13
  • Yeah, could be, but's rather unclear due to lack of grammar. I'm hesitant to edit it because I fear I might turn it into a different question than the author intends to.
    – Glorfindel
    Commented Feb 10, 2018 at 11:15
  • This is a good question. I have up voted and those who down voted should think again. The answer to this question is peculiar to the 2018 version of the Laws of chess thus any previous answers are not really relevant. Commented Feb 10, 2018 at 11:16
  • @melody FIDE or USCF rules?
    – D M
    Commented Feb 10, 2018 at 16:39

3 Answers 3


This is a good question indeed and a somewhat bizarre situation, which is not fully covered by the Laws. As you mention the opponent has completed an illegal move and you claim that. The relevant parts of the Laws are articles A.4.2., B.2 and 7.5.5.

The easy case is if your opponent has made an illegal move (that has been claimed) before. In that case they lose the game.

If this is a first illegal move your opponent has made in this game, however, then the arbiter will give you one minute extra time, the opponent's last move is taken back and they have to play any other move that is legal. This is where things become complicated. Your opponent has been checkmated and thus there is no legal move they can play. According to article 5.1.1 they should lose the game but only if the move producing the checkmate was legal, which it was not. Therefore, since your opponent cannot make any legal move, the game cannot continue but it has not finished and there is no result. Quite bizarre indeed.

The following is a somewhat bizarre solution to a bizarre situation. If the opponent is satisfied with a draw they could ask the arbiter to watch the next move and then make a move that leaves both kings in check. Then the arbiter will declare the game drawn according to article A.4.4..

If the opponent does not want a draw then the only solution that satisfies the Laws is that both players agree to correct the illegal move that caused the checkmate. This is allowed by article A.4.2. If they don't agree the Laws do not tell you what to do. In such situation, I, as an arbiter, would rule to correct that move nonetheless without penalizing the player who made it (i.e. you) since it was the opponent's responsibility to make a claim.

Current Laws of Chess are here.


It depends whether USCF or FIDE rules apply, and may depend on whether an illegal move was previously claimed.

Under the USCF blitz rules listed in my US Chess Federation's Official Rules of Chess 5th Edition, an illegal move results in a penalty of two minutes. There is a variation listed, however, where an illegal move results in forfeiting the game. In this case, capturing the opponent's king is listed as a way of claiming a win, rather than being its own illegal move.

The FIDE rules changed for 2018. It used to be that in blitz, an illegal move would allow the opponent to claim a win. However, this rule was changed, and now blitz is similar to normal chess in that a second illegal move by a player will result in a forfeit, and the first one merely results in a penalty.

As for which player can be penalized, it seems to be the player who took the king. See rule 1.4.1, which says "'capturing' the opponent’s king is not allowed." See also this article in which an arbiter says "As far as I can see, the player who completed the first illegal move is now entitled to claim the illegality." However, this article is from 2006 and isn't quite an identical situation; I can't guarantee that an arbiter today would rule the same way.

  • I won't comment on USCF rules neither on classical chess but the blitz game relevant part of your answer is not correct. You are referring to the Laws 2017, which are no longer in effect. Commented Feb 10, 2018 at 19:09
  • You're correct; the rule changed. I'll edit.
    – D M
    Commented Feb 10, 2018 at 19:30

If the opponent presses the clock he has finished an illegal move and you may claim a win. If he does not press the clock he may claim a win because of your illegal move.

  • The answer is not correct, the Laws have changed. You are not entitled to claim a win you can only claim an illegal move and article 7.5.5 applies, there is no guarantee that you will be declared a win after your claim. I have down voted. Commented Feb 10, 2018 at 11:06
  • The second sentence in your answer is incorrect as well. Commented Feb 10, 2018 at 11:09
  • @IAPetrHarasimovic But you can't forget about law A.4.2, since it's a blitz game.
    – D M
    Commented Feb 10, 2018 at 16:50
  • @DM Can you be more specific? I am not sure what you are referring to. I am aware of A.4.2, my point was that a player can claim before they make a move, pressing the clock makes no difference. Commented Feb 10, 2018 at 16:59
  • @IAPetrHarasimovic It's probably easier for me to just make my own answer.
    – D M
    Commented Feb 10, 2018 at 17:00

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