"Judicial legislation" is a term which is applied to a legal decision by those who disagree with it. You will never hear that term applied to a legal decision by those who agree with it.
And it is, of course, a highly subjective term - and therein lies the problem. Sure, no one can argue with the proposition that it is the legislature that enacts laws and it is the judiciary that interprets them. The trouble is, that, quite often, the interpretation of a law involves changing its effect.
What do you do with the following situation: A state legislature enacts a law that is violative of both the state and federal constitutions. Yes, Gloria, it DOES sometimes happen. Now what? The law winds up in some appellate court somewhere and it is held unconstitutional. In the example I have given, that is the proper ruling because my original premise is that our mythical law WAS unconstitutional from the git go.
What (predictably) happens next? Those who were opposed to the law applaud. Those who were in favor of it scream: "Judicial legislation!"
Of course, the opposite scenario can play out as well, where a perfectly valid law is struck down by an appellate court, ruling in error. In that one, it WOULD be judicial legislation.
Judicial legislation is easy to claim, but harder to substantiate. When does an appellate court's interpretation of a law amount to judicial legislation, and when is it simply a proper ruling?
All too often, it just depends on whose ox is being gored.
