Where your actions harm others. For example the Mohammed cartoons ended up upsetting a lot of people, and they set out to hurt a lot of people. That's not to say they shouldn't have been published but that is an example of someone's actions unknowingly harming others. The question however is how far accountability should go.
Of course should you set out to harm someone you deserve to be mutilated. I could care less about the sensitivities of someone who does this, anyone who seeks to harm others should cop it ten times as bad.