user27244: Say my opponent puts me in check. If I move my queen to block the check and it also puts my opponent in check, is that legal?

user7002: Yes, that move even has a proper name called cross-check
Nowadays most chess programs/apps/websites implement complete FIDE rules. A quicker way to check might be to set up the board that reflects your case, and see if the program allows you to move that way

user-1: It is indeed, allowed for you to do that. Because, your king is not being attacked and according to the chess rules, if your king is not being attacked, you are allowed to do anything to stop the check. When you put your queen in front of your king to block checks, you are basically defending your king. Thus, according to the rrules, it is allowed and I think it is encouraged because you are protentually putting your enemy's king in danger while protecting your king at the same time.

user26993: It is absolutly legal. A fun lichess study even did it some times: https://lichess.org/study/1LK3rCAK (it happened 5 times if I counted correctly, but not a lot with the queen :) )

user8860: It is legal to block a check with a move that also gives check.
This includes the case you ask about, where the blocker is a queen;
this is a key tactic in queen endings.
In general, a move that simultaneously parries a check and gives check
is called a cross-check.
This can happen with any of the three ways to parry a check:


The King can move, discovering check;

the checking piece can be captured, giving either direct or discovered check;
or

the check can be blocked, again with either direct or discovered check.



Tim Krabbé
cites two tournament games (Zarrouati-Brauckmann, Toulouse 1990;
Cardona-Conejero, Mislata (Spain) 2003) each featuring a sequence of
six(!) conecutive checks, and thus five consecutive cross-checks.
These show four of the five kinds of cross-check listed above
(including one where a Queen move both blocks and gives check,
as John asked).
The fifth kind, a block that discovers check, is illustrated twice in
G.F.Anderson's 1919 problem cited on Wikipedia's "cross-check" page,
and five times in the 1961 problem by the same G.F.Anderson —
including three cases where the cross-check is both direct and discovered,
i.e. a double check.

user27055: Yes, it is legal, since your king is no longer being attacked.

27244: <p>Say my opponent puts me in check. If I move my queen to block the check and it also puts my opponent in check, is that legal?</p>
 7002: <p>Yes, that move even has a proper name called cross-check</p>
<p>Nowadays most chess programs/apps/websites implement complete FIDE rules. A quicker way to check might be to set up the board that reflects your case, and see if the program allows you to move that way</p>
 -1: <p>It is indeed, allowed for you to do that. Because, your king is not being attacked and according to the chess rules, if your king is not being attacked, you are allowed to do anything to stop the check. When you put your queen in front of your king to block checks, you are basically defending your king. Thus, according to the rrules, it is allowed and I think it is encouraged because you are protentually putting your enemy's king in danger while protecting your king at the same time.</p>
 26993: <p>It is absolutly legal. A fun lichess study even did it some times: <a href="https://lichess.org/study/1LK3rCAK" rel="nofollow noreferrer">https://lichess.org/study/1LK3rCAK</a> (it happened 5 times if I counted correctly, but not a lot with the queen :) )</p>
 8860: <p>It is legal to block a check with a move that also gives check.
This includes the case you ask about, where the blocker is a queen;
this is a key tactic in queen endings.</p>
<p>In general, a move that simultaneously parries a check and gives check
is called a <a href="https://en.wikipedia.org/wiki/Cross-check" rel="nofollow noreferrer">cross-check</a>.
This can happen with any of the three ways to parry a check:</p>
<ul>
<ul>
<li><p>The King can move, discovering check;</p>
</li>
<li><p>the checking piece can be captured, giving either direct or discovered check;
or</p>
</li>
<li><p>the check can be blocked, again with either direct or discovered check.</p>
</li>
</ul>
</ul>
<p><a href="https://timkr.home.xs4all.nl/records/records.htm" rel="nofollow noreferrer">Tim Krabbé</a>
cites two tournament games (Zarrouati-Brauckmann, Toulouse 1990;
Cardona-Conejero, Mislata (Spain) 2003) each featuring a sequence of
six(!) conecutive checks, and thus five consecutive cross-checks.
These show four of the five kinds of cross-check listed above
(including one where a Queen move both blocks and gives check,
as <strong>John</strong> asked).
The fifth kind, a block that discovers check, is illustrated twice in
G.F.Anderson's 1919 problem cited on Wikipedia's &quot;cross-check&quot; page,
and five times in the 1961 problem by the same G.F.Anderson —
including three cases where the cross-check is both direct and discovered,
i.e. a double check.</p>
 27055: <p>Yes, it is legal, since your king is no longer being attacked.</p>
