I remember this being a thing that happened in the prison drama Oz, and thinking that phenomenon being BS, but I've heard enough stories of guards bringing in contraband that it seems to happen at an oddly high frequency. Is the prison system somewhat complicit with the drug running?
Yes you can buy drugs in prison freely. You can even buy cell phones but they have devices to detect cell phones in your cell.
Who brings them in? Possibly guards but visitors can also bring in a lot. Pretrial detention is tougher. The drugs are brought into prison and then smuggled into pretrial detention.
When I was locked up a few months ago, I would say on an average cell block maybe 80%+ of the prisoners were using drugs? Higher on some decks, lower on others. It would be a lot higher if people could afford them.
Edit: I'd never seen anything except weed before I went to jail. Inside jail I saw and was offered every single drug known to man in whatever quantity I wanted.
(Guards who are overworked and underpaid)