Being commanded to work on the Lord's day is much, much different than putting a man to death. Being commanded to worship another god (and I intend no sacrilege here) is also incomparable: worship has no meaning if it is not "in your heart," whereas a man is dead if he is put to death, and it doesn't matter one bit if anyone really thought it was right or wrong.
I suppose we're differing mainly on where to "draw the line": what we should leave to the government, and what we cannot excuse ourselves of.
From this definition, it seems that you're equating "justice" with "legal sanction." If I misinterpreted that, I apologize. I could not agree less - Laws confer no moral authority. What is just must also be fair and morally correct - it must be "the right thing to do." Ideally, justice and the law would always be in union, but that does not mean that one defines the other.
That's what our discussion revolves around, is it not? No one disagrees about the Law, just about whether it is Right. If the law were to be changed (say, in the next four years, capital punishment is outlawed everywhere on Earth), would that have any affect on whether it is Right or Wrong to put someone to death? No. Only on the acceptability of doing so.