In his 1945 essay "Politics and the English Language," George Orwell talks about how words can be used and misused to the point where they no longer have any meaning:

The word Fascism has now no meaning except in so far as it signifies “something not desirable.” The words democracy, socialism, freedom, patriotic, realistic, justice have each of them several different meanings which cannot be reconciled with one another. In the case of a word like democracy, not only is there no agreed definition, but the attempt to make one is resisted from all sides. It is almost universally felt that when we call a country democratic we are praising it: consequently the defenders of every kind of regime claim that it is a democracy, and fear that they might have to stop using that word if it were tied down to any one meaning. Words of this kind are often used in a consciously dishonest way.

Republicans have attempted to used the word "activist" to describe federal judges who do not rule in the ways they would like them to rule. Of course, Democrats have thrown the word right back, taking it and making it their own in describing some of Bush's controversial federal court nominees. Like "fascist" before it, the word "activist" has grown to have no meaning beyond "doesn't rule they way I want him to." One of the surest ways to discredit a political opponent is to call him or her an "activist," suggesting that perhaps he or she has an ideological agenda beyond merely enforcing, interpreting, or writing the law which is not in the best interests of the nation as a whole, but rather in the interests of a minority faction.

But is it really that subjective?

An op-ed in The New York Times suggests that "activism" is quantifiable. Operating under the assumption that "striking down Congressional legislation as an act 'of great delicacy, and only to be performed where the repugnancy is clear,'" the authors Paul Gerwitz and Chad Golder set about examining how many times the nine current Supreme Court justices engaged in that most activist of tasks, striking down Congressional legislation as unconstitutional.

The results are quite surprising. Based on their data, Clarence Thomas -- one of the court's most conservative justices -- was the most "activist," as he voted to overturn federal legislation in 65.63% of the cases where the constitutionality of federal legislation was in question. Breyer, one of the most liberal justices, was the least "activist," voting to overturn federal legislation in only 28.13% of cases where he could have done so.

The word "activist" has many definitions, and if used quantitatively, it has more meaning than if used qualitatively, where it can be slung pejoratively at any justice that a critic doesn't like.