Those who are sometimes called strict constructionists call it judicial activism when a judge first enumerates a right that is not explicitly formulated in the Constitution. The standard liberal response to this is that the 9th Amendment allows for rights that are not enumerated in the Constitution. Thus there are rights that are not listed, and therefore it's not judicial activism for a judge to proclaim what they are. This seems to me to be a fallacious move.
The 9th Amendment acknowledges the existence of rights that the Constitution doesn't enumerate. It doesn't say what they are. It's an interesting case of indeterminacy in law, because it declares that something is true while not filling out any details at all about what it makes legally true. So the right for gay people to engage in sodomy, for instance, is not in the Constitution on the grounds that the Constitution admits that there are some rights that aren't enumerated. The Constitution doesn't just leave it open that there are rights that it doesn't cover. It says that there are such rights. That's what's wrong with what some conservatives say. The rights explicitly in the Constitution aren't the only ones we have. Still, the Constitution doesn't say what those rights are, so it is going beyond the Constitution to claim that some purported right is one of the ones the 9th Amendment might refer to. It's therefore judicial activism.
One might object that, if a judge can't legally enumerate these rights that exist, then there must be no way to have them enter law and be enforced. That's not so. There's a constitutionally mandated way for new rights to be enumerated. You pass an amendment. That's what the 14th Amendment, for instance, was all about. It enumerated a right not made explicit in the Constitution. If judges had instead enumerated that right and not allowed the constitutionally mandated process of enumerating rights through amendments, it would have been judicial activism. If it had been ok for a judge to accomplish the same thing the way judges now seem to think they can do, then what was the point of going through the constitutionally-mandating and very difficult process of building that right into the Constitution? Doesn't it assume that the right isn't there, even if this was one of the rights that the Constitution says exist without enumerating?
The fact that the Constitution declares that there are rights that it doesn't specify does not tell us what those rights are, and it is indeed judicial activism to declare what one of them is from the bench if no amendment has placed it in the Constitution explicitly. The Constitution leaves it open that there's a right to privacy and that such a right to privacy gives a right to an abortion. It leaves it open that gay people have a right to sodomy. It also leaves it open that a brother and sister have the right to have sex with each other. It leaves it open that I have the right to marry my adult child. It leaves it open that I have the right to more than one wife. The way to determine which rights are the ones it's referring to is to make those rights explicit by affirming them explicitly in the Constitution. Otherwise we don't know if those rights are the ones it's talking about.
One thing that strikes me as unusual about this whole issue is what the nature of these indeterminate rights is supposed to be. Are they moral rights or legal rights? It makes no sense to say the latter. If the Constitution creates all these legal rights in the 9th Amendment without enumerating them, then it's basically making some legal fact that isn't about anything. It's a fact that some rights beyond the ones listed exist, legally. It's legally true that we all have rights that no one has ever said anything about. What makes those rights? They're declared to be rights, but there isn't any right that you could list that would be one of those, since it doesn't make any particular right be one of those rights.
This reminds me of the confused view that there are truths about the future of the form "Either A will occur, or it won't occur" without it being true that A will occur and without it being true that A won't occur. That's another discussion, but my resistance to the idea that the 9th Amendment creates legal rights seems to me to raise the same problems. How can it make it true that some rights exist without it being true of any right that it was thus created?
That's why I don't think it could be talking about legal rights. It must be referring to moral rights. We have moral rights that the Constitution doesn't give us as legal rights. This makes much more sense. If there are moral rights that aren't yet legal rights, then it isn't creating anything at all. It's just acknowledging that as other rights need to be enumerated legally, we should do so, because there are moral rights that the Constitution hasn't made legally binding.
Of course, now we have to be careful. Not every moral right should be legally enforced. I have the moral right to gratitude, but we don't want laws that require gratitude. For one thing, it won't be gratitude if it's compelled. For another, laws aren't about heart attitudes. They're about behavior. So the existence of moral rights doesn't go very far toward explaining why we should have judges constantly adding new legal rights that aren't enumerated in the Constitution. Therefore, I conclude that the idea doesn't make all that much sense either way. None of this moves me away from the strict constructionist view even a shred.
I do want to note one further element. There's one way in which Justice Scalia, Chief Justice Rehnquist, and other strict constructionists (whether they like the term or not; Scalia doesn't) are not pure strict constructionists, while Justice Thomas is closer to that. The former two accept precedent as grounds for deciding cases in ways that Justice Thomas does not. Now that Roe v. Wade is in effect, now that Lawrence v. Texas is in effect, it will be harder for weaker strict constructionists like Rehnquist and Scalia to pull away from these judge-created rights. They see the precedent as creating these rights, and those rights are thus real, even if they weren't in the Constitution and shouldn't have been created apart from an amendment.
The reason Justice Thomas doesn't accept precedent in this way is that he doesn't see that as a way to create legal rights. It's illegitimate judicial practice, and it doesn't create what only an amendment can create. This is the reason Justice Thomas is really in a category by himself with respect to his judicial philosophy, and this is exactly why he's my favorite justice. Precedent doesn't create rights because precedent is just judicial activism in the past. If you can't create rights that way, then why act is if the mere fact that the decision is in the past has created the right? Things that don't create rights now didn't create them just because they already happened. I can't see why Chief Justice Rehnquist and Justice Scalia don't see that.
Update: Brandon has an excellent followup to this at Siris.