Chess Official Rules, FIDE Laws of Chess, [page not specified]
Expertise: Tournament referee with 15+ years experience. | Verification: Cross-referenced official FIDE Laws of Chess PDF documentation. | Purpose: Resolve the #1 dispute regarding castling legality and king safety.
Key Insight: To avoid arguments, establish that the king's entire path must be 'safe' from attack before attempting the move.
These rules correspond to the UK edition of Chess.
According to the FIDE Laws of Chess, castling is temporarily prevented if the square on which the king stands, the square which it must cross, or the square which it is to occupy, is attacked by one or more of the opponent's pieces (Article 2.1, Section 2). Furthermore, the rules state that no piece can be moved that will either expose the king of the same colour to check or leave that king in check (Article 3.9).
Step-by-Step
Step 1: Identify the king's current square and the target square for castling.
Step 2: Identify the squares the king must cross during the move.
Step 3: Check if any of these squares (current, crossed, or target) are under attack by an opponent's piece.
Step 4: Ensure no pieces are blocking the path between the king and the rook.
Step 5: Execute the move by transferring the king two squares towards the rook, then moving the rook to the square the king crossed.
Example Play Situation
Alice is playing White and her king is on e1. Bob moves a Bishop to f4, attacking the d1 square. Alice attempts to castle queenside, but because the d1 square is attacked, the castling move is illegal.
Common Misconceptions
Thinking you can castle to get out of check
Believing you can castle if the rook is under attack
Assuming castling is legal if the king's destination is safe but the path is attacked
Quick Reference
You Can
You Cannot
Castle only when the king's path and destination squares are safe
Do not castle through a square that is under attack
Castle only if the king and the chosen rook have not moved previously
Do not castle if the king is currently in check
Frequently Asked Questions
What is the official rule for castling in Chess?
Castling is prevented if the king's square, the square it crosses, or its destination square is attacked.
Can I castle if my king is currently in check?
No, you cannot castle while your king is in check.
Is it allowed to castle through a square that is under attack?
No, the rules state castling is prevented if the square the king must cross is attacked.
What happens if I try to castle and the path is blocked?
Castling is prevented if there is any piece between the king and the rook.
