Fabio Rojas says quite possibly so. Excerpt:

You might doubt that Miers had a reasonable chance of maintaining O'Connor's moderating role in the court. But Miers had the background typical of a "drifter." You'll notice the leftward drifting conservative justices - O'Connor, Souter, Stevens, & Kennedy (sometimes) - all had a mixture of experience at the state and national levels, with occasional academic work. My guess is that working in varied environments - like state courts (Souter, O'Connor), state legislatures (O'Connor), governor's offices (Souter) and unconventional situations (Kennedy worked in various millitary venues; Stevens did a lot of work for the Illinois state government) - provided these folks with a richer sense of what the law is about.

In contrast, the hard leaning conservatives - Scalia, Thomas, Rhenquist, Alito, Roberts - seem to have fairly similar careers. After law school, there is often a stint in private practice and clerking, followed by a career flipping back and forth between academia and the federal government, either as an appeals judge, or as a legislative or executive assistant. This also applies to the reliably liberal folks: Ginsburg was an academic, before Carter appointed her as an appeals judge; Breyer's was an academic, and then appeals judge.

So my guess is this: A career dedicated primarily to judging, federal work, and academia probably indicates strong ideological commitment, either liberal or conservative. You have to be extraordinarily smart and sure of your political ideas to manage a long career either teaching the law or setting policy in a federal court or agency.