> s there some kind of international convention / agreement that says that policemen don't work abroad? I think you have got it backwards. There is no agreemen

> s there some kind of international convention / agreement that says that policemen don't work abroad? I think you have got it backwards. There is no agreement saying that they can. Staying in a foreign country is a privilege not a right. You are only permitted to do whatever your visa says you can do. In case of visa-waiver agreements, you can only do what the agreement states you can do, on top of that the government can pretty much kick you out at its own discretion citing vague reasons like national security.