Drift From Where?

I’ll be writing later this week about whether judicial appointments are ideologically predictable. But I find this assertion from Randy Barnett Barret rather problematic:

Everyone knows it’s all over but the spinning, but Lefties can take special solace in an odd trend: Liberal high court justices stick to their ideology on the bench while rightward picks have tended to drift to the left over time. Nobody can agree on why.

The poster children most often praised/cursed are Harry Blackmun, William Brennan, Sandra Day O’Connor, David Souter, John Paul Stevens, and Earl Warren — all of whom were nominated by Republican presidents and went on to side with the liberal bloc on key Court decisions. President Dwight D. Eisenhower ultimately described his appointment of Warren as “the biggest damn-fool mistake I ever made.”

It seems to me that Barnett is conflating two issues here: ideological drift, and judges who were picked for reasons other than ideology. Blackmun is the strongest example of a drift leftward over time, but between the fact that he was always moderate and his unique status as the author of Roe (who was consequently vilified by many conservatives), it seems equally clear that generalizing from his example would be foolhardy. O’Connor also drifted left, although this was partly her changing and partly the Court around her getting a lot more conservative. Stevens changed even less. But Brennan and Souter and Warren? They were never conservative by the standards of their time, there was never any particular reason to believe that they would be, and more to the point they didn’t change so much as start left and remain consistent.

And then, of course, there are counterexamples — Frankfurter, Black after 1960 — of liberal judges who became more conservative. Especially once you adjust for the fact that reactionary positions will tend by definition to be less popular over time, I don’t really see any evidence that ideological drifts are a one-way ratchet.