World Government

In the minds of many writers, a curfew is the piece of martial law no self-respecting dictatorship can go without. Specifically: the government legally forces everyone to stay inside past a certain hour at night and until a certain hour in the morning. While normally you'd expect the penalty for a rule like this to be a simple ticket or fine, the actual punishments you will find range from immediate jailtime at minimum to summary execution at most. Narratively speaking, the authorities can say that someone is a rebel just for being about; it also means characters can fight in major urban areas without risking innocent lives.