not in my book
Not according to one's opinion, beliefs, or values. A: "So what if I'm gaming the system a little bit to makes some extra money. It's harmless!" B: "Not in my book, it isn't. You're flagrantly exploiting a system meant to help people in genuine need!" A hit like that should never be tolerated in a game. Not in my book, anyway.
Not in my book.
Fig. Not according to my views. (Compare this with Not for my money.) John: Is Fred okay for the job, do you think? Mary: No, not in my book. Sue: My meal is great! Is yours good, too? Bob: Not in my book.