by Justin P (Tigard, OR)
Just had an interesting situation. I thought I had a square protected by en passant, but the program would not let me complete the move. Is there a rule that you can’t en passant out of check or is this a flaw in their coding?
you are perfectly right. If Black has moved the pawn from c7 to c5 then you (White) can capture it en passant.
But if the black pawn was placed at c6 before and Black played c6-c5+ then you CANNOT capture en passant because the pawn did not start moving from its original square c7.
In the position above Black has moved 1. ..c7-c5+ giving a check to the white king.
White can capture the c-pawn now playing 2. dxc6 which is a move en passant.
I hope this helps.