More than not normally. It would take the greatest danger possible for him to cross the line.
The three kryptonian criminals, is still a question of having been retconned or not thanks to Zero Hour and IC. Doomsday is still a current example. The Anti-Monitor, he knows it would take death to stop him.
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"I'm not smart so much as I am not dumb." - Harlan Ellison
Because they were more powerful than he was, and had killed every single person on the Earth of their dimension. He managed to depower them with the Red Kryptonite from their dimension, but they scoffed about the loss of their powers, saying they would get them back and come after him and his Earth. So Superman reluctantly decided to play executioner, and pulled out the Green Kryptonite to their horror. He held it on them until they were dead.
The event troubled him so much, he had trouble sleeping and developed a split personality, a more ruthless side who played vigilante in the Gangbuster costume.
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"I'm not smart so much as I am not dumb." - Harlan Ellison
No. He believes what he does, not matter if it's naive or not (Orion has called him that in the past.)
Batman is more deserving of being called hypocritical.
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"I'm not smart so much as I am not dumb." - Harlan Ellison
Just in his views about protecting people from harm, yet observe the huge body count the Joker has amassed, in the face of select principles Bruce holds to.
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"I'm not smart so much as I am not dumb." - Harlan Ellison
You'd think all those bullets that bounce off of him when he's around a crowd of people would have killed at least one person, could you blame a death like that on him?
I don't know if bullets should bounce off him with the same speed they hit, or just fall in a heap in front of him. I know artists like to make it look more dramatic by showing them going off in crazy directions.
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"I'm not smart so much as I am not dumb." - Harlan Ellison