That's just going by the book.
3 seconds sound clip from the Jaws (1975) movie soundboard.
You can hear this line at 00:12:15 in the Blu-ray version of the movie.
Quote context
[...]
- Albert, come on, you kook. Keep your arms up.
- Charlie, take me out to those kids, will you?
- Martin, you're going to shut down the beaches on your own authority?
- What other authority do I need?
- Technically, you need a civic ordinance or a resolution by a board of...
- That's just going by the book.
- We're really a little anxious that you're rushing into something serious here.
- This is your first summer, you know.
- I'm only trying to say that Amity is a summer town.
[...]