Was the killing of Osama in Pakistan legal?

We are not at war with Pakistan and Osama was not on the field of battle. What about the innocent bystanders did they have any reasonable expectation of safety (like his wife that was killed). I for one am glad he is dead but was it constitutionally legal or did we just witness a hit carried out by the US government live on CNN? What if Sweden decided to kill Tiger Woods at the next masters? Can you just kill at will because you want to? I don't know if it is legal but no one seems to be questioning it. Why? Are we no better than the terrorist? What happened to being Innocent till proven guilty. And after all the other intelligence failures I still want to see proof that he was behind 911. I want to see where he wrote the checks. There were no WMD in Iraq. Remember Colin and Condi with the powerpoint. We went to war with Afghanistan for Osama who was in Pakistan all alone. I don't want to see the pictures I want to see the proof!