user25976: If a king is not in check, can it capture an opposing chess piece?

user7297: Yes, it can, as long as the opposing piece is not protected. It's even possible when the king is in check; all that matters is the position after the piece is captured. If there is an opposing piece attacking the king, the move is illegal; if not, it's legal.
[FEN "kR6/2B5/8/8/8/8/6r1/6nK b - - 0 1"]
[startflipped ""]

1... Ka7 {This is Black's only legal move.} 2. Kxg2 {However, this is a legal White move.}

Black to move can't capture the rook, since it's protected by the bishop. White to move (disregarding the situation in the upper left corner) can capture the rook, since it's not protected, but not the knight, since the rook protects it.

25976: <p>If a king is not in check, can it capture an opposing chess piece?</p>
 7297: <p>Yes, it can, as long as the opposing piece is not protected. It's even possible when the king is in check; all that matters is the position <em>after</em> the piece is captured. If there is an opposing piece attacking the king, the move is illegal; if not, it's legal.</p>
<pre><code>[FEN &quot;kR6/2B5/8/8/8/8/6r1/6nK b - - 0 1&quot;]
[startflipped &quot;&quot;]

1... Ka7 {This is Black's only legal move.} 2. Kxg2 {However, this is a legal White move.}
</code></pre>
<p>Black to move can't capture the rook, since it's protected by the bishop. White to move (disregarding the situation in the upper left corner) can capture the rook, since it's not protected, but not the knight, since the rook protects it.</p>
