The context that these discussions often lack is that there are situations where it is considered acceptable for law enforcement to kill a suspect. An armed hostage taker being taken out by a sniper, for example. What is the rule that says that could be OK, but killing Anwar Awl Alaki is not?
Superficially, the rule seems like it would be based on whether capturing / arresting the person is not feasible, but doing nothing has a high probability of resulting in that person being involved in a violent crime (killing of hostages, participating in a terrorist act). Unfortunately, deciding if that is true for a given situation is of course a judgment call. But to simplify it down to "the government shouldn't kill people without a trial" overlooks some things that need to be considered. Could he have been feasibly arrested? What would have been the consequences of doing nothing?
Superficially, the rule seems like it would be based on whether capturing / arresting the person is not feasible, but doing nothing has a high probability of resulting in that person being involved in a violent crime (killing of hostages, participating in a terrorist act). Unfortunately, deciding if that is true for a given situation is of course a judgment call. But to simplify it down to "the government shouldn't kill people without a trial" overlooks some things that need to be considered. Could he have been feasibly arrested? What would have been the consequences of doing nothing?