Regulated mass murder is still mass murder.
The argument takes place at three levels, each with their own sphere of responsibility.
(1) the common ordinary citizen, who does not legislate,
(2) the legislator or lawmaker, who does
(3) the theorist, who works out a legal philosophy
Were I a common ordinary citizen in Germany during the war, should I have insisted that nothing be done for the Jews until first a just and lawful understanding of the human person replace the final solution?
Were I an official, in some legislative capacity, should I have insisted that I sign no document until first a just and lawful understanding of the human person replace the final solution?
Perhaps I place less emphasis on the efficacy of a Constitution than the efficacy of a people. In a certain way, the people are above a constitution because only a people perceive a higher law than the constitution (cf. Hayek).