You wrote:
But what if we throw out that first claim? Why can’t a claim of judicial activism be “the court decided the question under a subjective motivation other than legal correctness?” In other words, “judicial activism” as a claim not about the correctness of a legal decision, but about the content of the consciousness of the decision-maker?

I think that using a subjective measure of the judge’s intent only takes you so far. Everyone agrees that a judge consciously trying to subvert the law is a bad thing. It’s the easy case and also the case that to my mind never happens. In a public debate that category of judicial activism is all but useless because you will never establish intent. I would rather get away from including such a subjective element because I don’t think an argument of the sort “The decision in xyz is ludicrous, Judge A must have intended to violate the law and make a mockery of the constitution” is useful. It will just never go anywhere.

You also wrote:
Alternatively, suppose the law is indeterminate? Which of course it is - this is the “it’s all politics” notion. If “legally correct” is a term that doesn’t actually signify anything, then wrongness in a judicial decision can only attach to political (or factual) errors. Could “judicial activism” then mean “judicial action which is contrary to our notions of the proper scope of judges, notwithstanding the legal authority they may plausibly claim?”

I agree that if you deny that law is at least (to some extent) determinate, you end up in the “all is politics” notion. But why then care about about the “proper” scope of judges, and “plausible” claims to legal authority? If judges can’t tell what the law requires or doesn’t require, how can anyone tell what is proper or plausible? Put differently, if you go there at all, I think you are forced to go all the way: everything is politics, which means that everything is about power and never mind such niceties as proper scope or legitimate legal authority.

Of course I don’t think that the law is indeterminate. I agree that it is only determinate in some percentage of cases (95%? 98%? you have to control for all the fact that only the pathological cases ever go to court), but I don’t buy into a positivist “scientific” proposition that it must be 100% determinacy or it is nothing (I realize there is a bit of a contradiction in terms in there). I think that bit of indeterminacy in the law only means that the work of lawyers and juges is creative; not that it is arbitrary or irrational. In fact the law addresses these issues by requiring written opinions of decision makers (wouldn’t make much sense if no disagreement over the outcome were conceivable) and by proceduralizing the process of decision-making.

Thanks for writing.