What is an "activist judge"?

A New York Times article describes an attempt to develop an "objective" standard for numerically ranking Supreme Court justices on a scale of activism. Justices are ranked on this scale according to how many times they have (1) voted to overturn a federal or state law and (2) voted to overturn one of the court's own precedents:

Lori Ringhand, a professor at the University of Kentucky College of Law, examined the voting records of the Supreme Court justices from 1994 to 2005. Because judicial activism is a vague concept, she applied a reasonable, objective standard. In the study, which is forthcoming in Constitutional Commentary, justices were considered to have voted in an activist way when they voted to overturn a federal or state law, or one of the court’s own precedents.

As for the first issue, voting to overturn a law: if a law is blatantly unconstitutional, is it virtuous to vote against overturning it?

As for voting to overturn one of the court's own precedents, is that necessarily bad? I think that few people today would argue that it was wrong for the Supreme Court to overturn the "separate but equal" segregationist doctrine of Plessy v. Ferguson. And what if the precedential case and the new case are only partly similar -- then the decision of whether or not a justice voted to overturn precedent would be arbitrary. Also, in some judicial decisions, the justices might uphold one precedent and overturn another.

Judge John E. "I am not an activist judge" Jones III said, "People term 'activist judges' judges they don't agree with." Ed "It's My Way or the Highway" Brayton has been saying the same thing. Brayton absurdly argues that everyone who uses the term "activist judge" has no coherent definition for it and uses it inconsistently, and that therefore the only possible meaning of the term is that the person using the term does not agree with the judge:

. . . .the phrase "judicial activism" means whatever the person using it wants it to mean at any given time. The ADF [Alliance Defense Fund] uses it in many different ways, some of which apply perfectly to cases they claim to support and not to cases they deny. They simply have nothing approaching a coherent definition. All it means, as I've been saying for years now, is "I don't like that ruling." The actual use of the phrase is utterly incoherent . . . .

There is a problem that people do not agree on what the terms "activist judge" and "judicial activism" mean. I see no reason why "judicial activism" should be defined as being different from any other kind of "activism," a term that the Merriam-Webster's online dictionary defines as a "doctrine or practice that emphasizes direct vigorous action especially in support of or opposition to one side of a controversial issue." So to me, "judicial activism" is any arbitrary, capricious, or overreaching judicial ruling or philosophy that is intended for supporting one side of a controversial issue. Most of Judge Jones' statements and actions that I have criticized in this blog eminently qualify as "judicial activism" under this definition.

Wikipedia gives the following definitions of "judicial activism":

According to Merriam-Webster's Dictionary of Law, judicial activism is "the practice in the judiciary of protecting or expanding individual rights through decisions that depart from established precedent or are independent of or in opposition to supposed constitutional or legislative intent". According to Black's Law Dictionary, judicial activism is "a philosophy of judicial decision-making whereby judges allow their personal views about public policy, among other factors, to guide their decisions, usu. with the suggestion that adherents of this philosophy tend to find constitutional violations and are willing to ignore precedent." Different legal scholars and judges may have different definitions of judicial activism.

Since Wikipedia's above definitions from two authoritative sources are a little narrow for my tastes, maybe I should not use the terms "judicial activism" and "activist judge" at all.