Both legislators and judges should consider natural law and justice, but in different ways. Legislators should consider them in order to frame the statutes; judges should consider them in order to understand the statutes.
According to some conservatives, this view is terribly wrong because it invites judicial activism. They agree with the first part of the statement -- that legislators should consider natural law and justice in order to frame the statutes -- but they say judges should not consider them at all. If judges are allowed to do so, they fear, then judges will inevitably substitute their own opinions about right and wrong for what the statutes mean. This is much like the Reformation’s idea about how to prevent distortions of sacred text, but instead of sola scriptura, the rule is sola statutum.
Perhaps solum statutum would work if it were possible for judges not to consider anything outside of the statutes. But it isn’t, because the statutes are not self-interpreting. No texts are. No matter how earnestly the interpreter defers to the meaning of their words, this meaning depends on innumerable things beyond and outside of them – yes, on things like justice. If you get those other things wrong, you will not grasp the law either.
If I am right – if not to consider those other things is literally impossible – then if you push them out the front door, they will sneak in through the back. But in this case, the demand not to consider them does not reduce the danger of judicial activism: It increases it, because it is much more difficult to scrutinize considerations we pretend not to be thinking of than considerations we admit we are thinking of.
Some judges say that they are forbidden to look beyond the text of the statutes by their very oath of office. It would be a pretty paradox if the oath did require impossibilities, but fortunately, it doesn’t. Look it up: They promise to administer justice and to uphold the laws. Both duties are binding; neither may be violated; neither may be subordinated to the other. The statutes do not take the place of justice; justice illuminates the meaning of the statutes themselves.
A highly placed federal judge once suggested to me that if construing the meaning of the statutes does require understanding the meaning of justice, then the legislature has done a bad job. It should use clearer words which don’t carry such a moral charge. He had a point, for one can certainly replace words which are more likely to be abused with words which are less.
But he also overstated his point, for one cannot replace words which need interpretation with words which interpret themselves; there are no such things. Ultimately, all language points beyond itself to the real world. If you cannot fathom the world, then you cannot fathom the language, and the just and unjust are features of the world.