How can they show people using drugs on Intervention?

How is it legal to show real-life documentaries of people shooting up heroin and other illegal drugs?
By the way, I’m a libertarian, so I’m for decriminalizing most drugs and shutting down the whole stupid money-wasting war on drugs. I think some of you inserted your own imagined tone to my question. I’m all for the show, and I love watching it, but I’m just thinking it’s hypocritical that the police can set up sting operations and arrest people before they’ve even done anything- just said they want to (I mean, attempting to get a prostitute, attempting to buy drugs)- but they can film someone straight up using heroin on these documentaries and no arrests are made.

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