by the book
Meaning: If you do something by the book, you do it strictly according to the rules or the official procedures.
- The match officials in the golf tournament acted strictly by the book when they disqualified a player for marking down the wrong score on his score card.
- The embassy officials process visa applications by the book these days, so it's harder to get one than it was when they weren't so strict.
When they arrested the suspected killer, the police did everything by the book. They