I read in the description of the interrogation chamber you can get information by interrogating prisoners and I never have been able to find the edict to do this since I had the game back when it was new. Any information/help on interrogation? This has bugged me for years but now I decided to ask since I can't find an answer anywhere.

there is no such thing in this game. When you put rivals in the cooler, you can either make them work for money or brainwash them.

Very odd, because there is 2 references to an interrogate edict in various in-game descriptions. Maybe it was ditched in development? Wish it was there though, make it much easier to find new trading lanes.

It's in the campaign mode. I have no idea if it's ever possible in sandbox, but there's one mission I've encountered thus far where you have to build an Interrogation Chamber and use it to squeeze the details of the traitorous Henry Morgan's return out of your captives.