This does not address Norrin's point. He was making a moral statement; you are shifting ground into a legal one. No, if you commit murder a police officer isn't going to arrest everyone in your house. However, a preacher might suggest that those around you were a bad influence, or that they should have stopped you or talked you out of it. And he would have a point.

The law must stop short, for practical reasons of the public good, from moral exactitude. But that doesn't mean we must do so. We are not the law.

W/r/t government atrocities, as I said before, no government can exist without public support, and that's true whether or not the public support is articulated and expressed through the convenient medium of elections. That makes the people responsible, to a degree, for what the government does. Only if the government acts in complete secrecy is this not true, and even then, the people are still responsible for supporting a government with the propensity to do such things. For example, even if the German people didn't know about the Holocaust, they certainly knew about Krystalnacht, the Nuremberg laws, and the harsh antisemitism of the Nazi regime, and they were responsible for supporting a government with that kind of propensity.

Certainly in a democracy (getting back to the thread topic), the people are responsible for what the government does, which includes the U.S. decision to use nuclear weapons on Japan. Even though the Manhattan Project was top secret and very few knew about it, the people certainly knew after the fact -- and President Truman was reelected three years later.