Illegal moves and their penalties
What counts as an illegal move over the board, and what happens when one is played.
The idea
An illegal move is taken back, and your opponent gets extra time.
- The bishop looks along the diagonal at the king.
- The knight stands in the way, so it is pinned.
- Moving it would leave the king in check: no knight move is legal.
In a game: Before you press the clock, check that your king is not left in check.
How the lesson begins
An illegal move is one the rules do not allow. Online the site simply will not let you make one. Over the board you can, by mistake.
Here the white knight is pinned: the bishop on b4 looks through it at the king on e1. If the knight moved, White’s own king would be in check, so no knight move is legal.
A question
White is in check from the rook on e8. Which of these moves is legal?
Show the answer
Kf2.
Right. The king steps off the e-file to a square nothing attacks.