Early next month, the Supreme Court will hear arguments in a case that will be a test as much of the five conservative justices as of the law they will review. Ever the optimist that principled reasoning will prevail, I’m betting that the conservatives will pass the test (hoping for once to be proven right!).

The issue in McCutcheon v. FEC is the limitation on aggregate contributions to federal campaigns. To simplify it radically: under federal law, individuals can give up to $2,600 to any candidate in any election cycle. But the total amount they can give to federal candidates in aggregate is capped at $123,200 per year. So, for example, while I can give $1,000 to any candidate I want, I can’t give that much to more than 123 candidates in one year (poor me!).

Critics of the law say it “abridges” their “freedom of speech.” They should be allowed, these critics argue, to give as much as they want in aggregate, so long as the contribution for any candidate is limited to $2,600.

Since 1976, the Supreme Court has been pretty clear about the basic question that must be answered in a case like this. The First Amendment limits Congress’s power to regulate political speech—severely, and rightly, in my view. Only if Congress can show a “compelling” interest can it restrict the freedom of individuals to contribute to political campaigns. Even then, the restriction must be “narrowly tailored” to the interest the government seeks to advance. “Good enough for government work” just doesn’t cut it when the issue is political speech.

The only viable “compelling interest” that the court has recognized in campaign-finance cases is “corruption.” Congress can limit individual contributions to $2,600 to avoid corruption, or the appearance of corruption. And by “corruption,” the court has meant “quid pro quo” corruption. If limits were much higher, Americans could rightly fear that contributions were being given in exchange for some government benefit. If anything is, that is “corruption.”

But as the petitioners in McCutcheon will argue, if the contributions of an individual to any particular candidate aren’t big enough to raise the concern that they are given in exchange for a government benefit—if each on its own, in other words, is not “corrupt”—how does aggregating those contributions somehow convert them into something that is corrupt?

For example, no one would think that a $500 contribution to a congressional candidate is evidence of corruption. But if you gave $500 to every Democratic (or Republican) candidate, you would exceed the federal limits. How does aggregating non-corrupt contributions render them corrupt?

Here’s where the judicial philosophy of the five conservatives becomes relevant. At various times, and with differing vigor, the conservatives on the Supreme Court have called themselves “originalists.” That means that they’ve committed themselves to a particular method of interpreting the Constitution and the Constitution’s constraints on Congress. For an originalist, if Congress can regulate “corruption,” then what “corruption” is should depend upon what the framers of the Constitution thought “corruption” to be. And so if the Framers thought “corruption” meant just quid pro quo bribery or the like, then Congress’s aggregate limits are going to have a rough time.

But this is where things get interesting, for this may well turn out to be a case where originalism is ideologically surprising. Because as legal scholars such as Zephyr Teachout have argued for a very long time, in fact the framers had a much richer conception of corruption in mind than one limited to quid pro quo corruption alone. And so while the modern conception (limited to quid pro quo) may not justify aggregate limits, the original conception just might.

I wanted to test that theory the framers meant something more by "corruption" than "quid pro quo" corruption alone. So I asked some researchers to collect every use of the term "corruption" in the debates surrounding the adoption of the Constitution. What would they have meant by "corruption" in 1787? What power would they think that Congress should have if Congress had the power to regulate "corruption"?

Using the online database ConSource.org and others, my researchers found 325 examples in the period surrounding the adoption of the Constitution. They then coded the examples to understand how the term was being used.

Their findings were dramatic: Sometimes, no doubt, the framers used the term “corruption” to refer to an improper quid pro quo. But not often: By the researchers’ count, only six times out of the 325, and all of them referring to cases involving individuals. In the sample generally, moreover, talk about individual "corruption" was less than half (43 percent). Instead, by “corruption” the framers were ordinarily speaking of institutions—like the “corruption of Parliament”—and ordinarily that "corruption" was unrelated to any "quid pro quo."

Indeed, the most common kind of institutional "corruption" that they discussed was an institution that developed an “improper dependence.” Fully 29 examples—almost five times the number of “quid pro quo” examples—were cases of “improper dependence.” Their concern was to craft a constitution that would avoid institutions becoming improperly dependent—as Parliament, for example, had become improperly dependent upon the king. (I put the full database in a Tumblr if you’d like to read through the examples: http://ocorruption.tumblr.com ).

These conclusions should matter to the committed originalist. The Framers were pretty clear about the dependence they intended Congress to have. (Or at least the House of Representatives: the Senate was different at the founding, since it was appointed by state legislatures). As Madison put it in Federalist 52, the House was to be “dependent on the People alone.” But by “the People,” Madison meant all the People. “Not the rich,” as he wrote in Federalist 57, “more than the poor.” (OK, and not women or blacks at all, but later generations would fix those errors).

From this perspective, then, an “improper dependence” would be a Congress that had become dependent upon the rich. For—surprise, surprise!—“the rich” don’t represent “the People.” And so a regulation designed to reduce the dependence upon the rich—by, for example, limiting the extent to which Members of Congress were dependent upon the rich—would be precisely tailored to the end of reducing “dependence corruption.” From Madison’s perspective, then, the limits challenged in McCutcheon would make perfect sense, because for Madison, and the Founding generation, “corruption” meant something more than "quid pro quo" alone.

Of course, it’s always possible for a Justice of the Supreme Court to say, ipse dixit, that for him, and hence for the court, “corruption” will mean just “quid pro quo” corruption. After all, courts make up things all the time, sometimes for good, and sometimes not. But the critical point that this research suggests is that a committed originalist shouldn’t be so narrow. For a committed originalist, a law aimed at reducing the dependence of Congress on the rich is a perfectly ordinary example of a law aimed at reducing “corruption.”

For a committed originalist. We’ll soon see just how committed to their philosophy the five originalists on the Supreme Court are.