once a president

it always baffles me to watch saddam hussein on tv, as a prisoner. how on earth can a foreign soldier invade your country and put your president or prime minister behind bars and then present to the people as a prisoner? is this acceptable international law, international code of practice? who is the next president or prime minister to be turned a prisoner? can another country do it instead of the usa and be acceptable to the world community, or will the world community just squeeze their own balls and keep quiet, can't do anything about it? hey, our capital punishment is seen as barbaric by some nations. can they use that as an excuse to invade us and put our prime minister behind bars too? why are the iraqis happily going about trying their own president because a foreign power tells them to do so?