Sure. You need to be qualified to do that. A doctor can do that for the short term. And then a judge and a court has to make such decisions. I think in the real world they're the only ones allowed to do that, to adults at least. And it involves lots of paperwork, hearing experts and so on. But also in real life, captains get some extra rights and duties, if they're far out there, on their own. They can definitely lock up unruly people or make difficult decisions that need to be made on the spot. For everyone else, not so much. However, I think there are some exceptions. I'm not a native english speaker so I don't know the exact legal term... But next to self-defense, there are other laws concerning emergencies, justifiable emergency, necessity as justification, good samaritan law...? I don't know how we call that. But I'm pretty sure I could stop someone harming themselves, against their will. In dire circumstances. It wouldn't be fun though, and the last resort to avert serious damage. It's certainly problematic. And I think it has to meet objective standards. It can't be construed, or it won't apply. It's complicated. And on the other side we also have failure to provide assistance where I live, which I'm not sure if it's a law in the States.