Can I forcibly prevent someone from committing a crime?

1

State laws vary. In some cases you have the right to use "reasonable force" to detain a felony suspect for official arrest by the police, however, you would be taking the risk that the felony charge eventually gets dropped and you get sued for false arrest damages for your trouble. Some states have a "merchants" exception under which the owner of goods has a privilege to detain a shoplifter for the police, using only as much force as necessary to obtain compliance.

No. See, they haven't committed a crime. That whole "innocent until proven guilty thing." Until they've gone to court and a judge say guilty, they're innocent. If you see someone rob a bank, you actually see them use a gun and take the money, that person is still innocent. Because you don't get to decide innocent or guilty.

No citizen has the right to take the enforcement of the law into their own hands unless it is to protect the life of another citizen.

Basically, of you see someone stealing something, don t apporach them, film them. It can legally be used as evidence in court and could therefore lead to their prosecution. If you forcibly detain them then you could be the one being prosecuted.

Law regarding citizens arrest vary WIDELY. The ONLY thing coming close to a universal rule is that if you have to ask, you WILL break the law yourself. Unless you would be justified in using force in self defense, any use of force almost certainly crosses the line.

You must have a death wish. You have thr "right to stop someone, you do not have the right to *steal* stolen property

Not usually. You could be charged with assault in many cases.