Now that SCOTUS deliberation over the constitutionality of portions of Obamacare is going much worse than most liberals predicted, left-leaning pundits are screaming "judicial activism!" which is cute, though I understand the frustration. As Scott Lemieux reminded David Frum:
[C]onservatives on the court (and much more so off the court) do spend a lot of time railing against “judicial activism.” What the conservatives on the Court absolutely don’t do is oppose “judicial activism” in practice.
And this should not be surprising. As a practical matter, to refuse to rule in an "activist" fashion is to defer slavishly to precedent, whatever it might be, whether one believes precedent was based on "activist" reinterpretation or ignorance or error. Even then, interpretation of the implications of relevant precedent requires an interpretative framework. The least "activist" interpretative framework would be one in which judges attempt to interpret the relevant body of law as closely as possible to the intentions of the proximate lawmakers, whether they be legislators or other judges. Nobody does this. And why would they? It's stupidly arbitrary. What if the intention behind prior rulings was ignorant, or perniciously ideological, or harmful?
Were we to make slavish deference to precedent universal law, ala Kant, we'd end up with what a sort of path-dependent judicial drift--tiny but unavoidable interpretative mutations piling up until the law ends up in places no one finds desirable. Interpretative frameworks that push the law toward substantive ideals save us somewhat from the problem of arbitrary, path-dependent drift. But they create another kind of arbitrary drift, as rival frameworks push the interpretation of the laws in incompatible directions. This can, again, leave us in stupid places no one ever had in mind. The only rescue is the occasional "activist" saltative leap that either ignores or radically reinterprets precedent in order to restore to the law the coherence of principle, for a while at least.
"Originalism" is not a non-activist interpretative framework. An "originalist" framework applied to the interpretation of non-originalist precedent predictably generates "activist" decisions. That is why, as I've argued before, originalism is just one among many philosophies of the "living constitution", and does not differ in fundamental method from the progressive "second-bill-of-rights" philosophy, which attempts to reinterpret the law such that over time the accumulation of progressive precedent codifies certain basic rights unfortunately omitted from our antique constitution. Both philosophies seek to rewrite the law, as it now stands, better to conform to some external ideal. Originalists seem to think their ideal has more legitimacy than the judicial New Dealers because today's law bears an imagined evolutionary relationship to the thing they have in mind. The orginalist argument is somewhat like the argument that although men now wear baseball caps instead of fedoras, they should begin wearing fedoras because they used to wear them. But that is not actually a good reason to wear a fedora instead of a cap.
Anyway, if you're going to have a written constitution with strong judicial review, there's just no way around judges deciding some cases according to their personal ideological preferences, which is why everybody cares so much about the partisan affiliation of the guy who gets to nominate people to the SCOTUS. Norms of deference to precedent and legislative intent, which limit just how activist courts can be in practice, are healthy. But every now and then court majorities are going to spend down their fund of legitimacy in "activist" efforts to impose/block what they see as good/bad policy or establish/block what they see as a good/bad precedent, and this isn't at all a bad thing.