system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why, in documentaries about drug users, do the people using drugs not get arrested once the police see the video?

It seems like video of the person doing the drug is ample evidence that they are doing it, right? Why can't the police just be like "oi! get in jail"
gpt
Several reasons, including the fact that there's no way to prove conclusively what they're smoking, swallowing or injecting. There's no real legal difference between actual drug use shown in a documentary and that depicted fictitiously in a movie. There's no way to tell them apart.

There's also often uncertainty about when or where the use happened.