Alexander Hamilton described the role of the court this way: “The interpretation of the laws is the proper and peculiar province of the courts. A constitution, is, in fact, and must be regarded by the judges, as a fundamental law. It therefore belongs to them to ascertain its meaning, as well as the meaning of any particular act proceeding from the legislative body.”
Even in Hamilton’s time, it was recognized that there would be room for interpretation of the Constitution. That interpretation, according to Hamilton, belongs to the justices. But you seem to be saying that there is some objective, “non-political” standard by which their interpretations should be measured. If that were the case (and I’m not sure what that standard would be), then the interpretation wouldn’t really belong to the justices, would it?