Every now and then I volunteer for an association, organizing big role play events in my country (by big I mean several days with between several hundred people, so nothing at the national scale, but big enough nonetheless).

There I act as one of many game masters, creating the game to entertain people,... but I'm also meant to make people apply the rules whenever I can, be sure there are no cheaters etc...

The association has a responsibility towards the players somehow, and even though as a volunteer I risk nothing (legally speaking) if rules are not respected, it's part of our duty to make sure everyone is safe, and to some extent that the law is applied. I'm not there to play the police, yet I can't let people commit small (or not-so-small) crimes without doing anything, because the association might suffer from it. 

This year, I eavesdropped a little while waiting for someone, and heard people talking about what they were smoking. They were absolutely not trying to hide they were having fun with good old cannabis, and to the smell of it, indeed it was drugs they were smoking.

Here lies my problem. Smoking this is forbidden in my country. If many people are doing it, it will be very bad press for the event. Moreover, I'm talking about an event with childrens of all ages, pregnant women sometimes etc... thus people who must not be impacted by passive smoking from this drug.

So, I think I should step in and stop these people from taking drugs, right? But here comes the tricky part. It is a well known fact in my country that a large majority, especially for people of my age, is in favor of the decriminalization of cannabis. So, should I step in and stop this, I can be a hundred percent sure a lot of people will see it very negatively.

I was told in such case I could ask people to stop smoking, and in case of repeated offence, to seize their "cigarette", or even exclude them from the area of play (which is a private property rented by the association). 

My problem is: I have a duty to perform, yet I'm absolutely not a member of law enforcement, thus the only authority I got comes from the respect players have for their game master. Nothing more. 

**How can I approach these people to stop smoking drugs in the event area without causing a drama?**