Does Aquinas Really Say That?

I found myself reading back through some threads of Commonweal posts -- I'm not sure why these fits of madness take me at times, but they do -- and I stumbled across this Cathleen Kaveny piece where she's arguing that Catholic schools should not dismiss teachers who turn up pregnant out of wedlock.

There are real issues to discuss on the topic, and I don't think there's a single one-size-fits-all answer, but predictably Kaveny's reasons are pretty bad. One bit in particular stuck out to me, however. She says:

Everyone knows that St. Thomas Aquinas says that an unjust law is no law at all, but rather an act of violence (actually, Aquinas’s reasoning is much more subtle on this question, but that is for another day). But he also says something that gets far less attention: a law that imposes a burden unequally upon members of the community is also an act of violence–even if it furthers the common good.

Now, I have a pretty good idea how she's getting to the former, but I'm rather mystified as to what in Thomas she's working off of to get to the latter. I'm certainly not prepared to make a claim that he doesn't say that. I haven't read all of Aquinas and I don't consider myself enough of an expert on him to have an unerring sense for what he would say, but it does seem rather off to me such that I'm skeptical. She provides no citation or elaboration. Does anyone know what she may be referring to?

Perhaps it's my post-enlightenment views about law and government cropping up, but it seems to me that most laws probably impose a burden unequally upon members of the community. Indeed, I would imagine that Kaveny herself supports a number of such laws. For instance, very few people want to play around with trading billions of dollars in risky financial investments, and thus necessarily any laws we impose to prevent such people from inadvertently crashing our banking system would disproportionately burden that small group of people able and eager to do such things. However, I don't think that Kaveny would suggest that the fact that these laws burden those few while not touching people like her or me would make them unjust. Indeed, she'd probably argue that if such laws protect the common good they are morally obligatory.

Of course, what she probably means is laws where the unequal burden falls upon groups that she perceives as oppressed. But if that's the case, it's hardly a general principle. And either way,
I'm a little skeptical that she's pulling this from Thomas -- if only because she is phrasing it in such a modern way.