If I were to shoot a documentary where illegal drug use was featured throughout (just pot) is there any possibility of legal action being taken against the filmmaker or subjects?
I don't know if they'll take action against you, but think about it. You're FILMING people doing something that's (unfortunately) illegal. Film could be used as evidence for the authorities. I don't think these people you want to film would want to have that risk. But you're in LA, right? As in Los Angeles? Correct me if I'm wrong, but I heard that they legalized pot there.
I have seen many shows that showcase drug use (Dr. Phil, Oprah, Etc.) They all show the actual drug use. I dont know that you would run into a problem, but I would ask a lawyer.
It's legal for medicinal use on the state level, but it's still illegal on the Federal level. However that being said, one of the Obama administration's first moves was to stop the "federal raids and enforcement on medical users" and to take the aim of letting the state have more authority over this.... so it probably won't be a problem in Cali if you're filming cancer patients and stuff. If you end up getting arrested, be sure to film it though (with a cop grabbing the camera saying "shut that damn thing off") and then you'll have a great PR campaign for your movie!
It also depends on how you portray it- if you show people being happy and functional (ei. driving) while on pot, it might piss off all the Illuminati drug lords who depend on the un-taxed revenue for their plans of world domination. But if you're portraying it as the Devil's Herbs, then you'd probably have no trouble at all from!
Just remember, if anyone asks, they were all smoking oregano.
There's a documentary series on A&E called "Intervention" where they show drug use all the time. I'd imagine that filmed evidence of drug use could only be used after the fact (they bust the subjects in the act or for possession, and use the footage as further evidence) and not as cause for arrest, but I'm not entirely sure.
You have to register to gain access, but maybe within there you'll find a link to a producer and could ask them directly what legal ramifications exist for filming drug use.
For something like this you definitely need a lawyer and insurance. You can document anything, where you will get in trouble is when you participate, contribute, or someone gets hurt due to the production. If someone wants to buy drugs, don't offer them a ride, you have to let them do their thing and follow them. This is not legal advise, you definitely need a lawyer.
Oprah, Intervention, etc. are produced by well financed companies who have professional legal talent on staff. They are also (arguably) disseminating "news", so are covered under various legal statutes protecting sources. The real point here is that because of their large financial resources and legal staff they would be extremely difficult to prosecute successfully. Secondly, because they all take a strong anti-drug stance it is deemed beneficial to society.
I would strongly suggest that you get some real legal counsel just to cover your backside.