When the Supreme Court is in session, constitutional law comes to the fore of American politics. To explain how the Court makes its decisions and why these decisions matter, it can be useful to think of constitutional law as raising two distinct types of questions.

First-order questions involve decisions about the fundamental rules governing our democracy and society. They frequently implicate the limits on government power and often are the sexy kinds of legal issues that make headlines. Think of the debate on whether state universities may use race-based affirmative action procedures.

Second-order questions involve decisions about who has the authority to decide the first-order questions. For example, should the courts or the president determine whether drone strikes against American citizens abroad are constitutional? What are the limits of the president’s ability to wage war without Congressional approval?

Though not nearly as headline-ready as the first-order questions, second-order questions are nevertheless important and interesting in their own right. And though they are often politicized, they nevertheless have the potential to attract a bipartisan consensus. As Professor Akhil Amar explained, they raise the distinct possibility that “even if people violently disagree about what the law in a given area was or ought to be…they [might] nevertheless agree that the legal decision in that area ought to be made by a given legal institution…acting under certain specified rules of operation.”

NLRB v. Noel Canning, a case currently before the Supreme Court, brings both first- and second-order questions to the fore. The first-order questions (and the questions on which the Supreme Court officially granted review) concern the scope of the president’s recess-appointments power. But while the scope of the president’s recess-appointments power is undoubtedly interesting in its own right, what makes Noel Canning a particularly fascinating case is the second-order constitutional question underlying it: Who ought to have the authority to define the scope of the recess-appointments power?

First, some context. In general, high-level presidential appointments require approval by the Senate. The recess appointment power allows the president to temporarily appoint nominees without Senate approval while the Senate is in a recess. While this provision was originally intended as a practical safety valve to keep the federal government running, particularly in the Founding Era when the Senate was often not in session (and when calling senators back to Washington solely to approve nominees was impracticable), it has since become a tool employed by presidents to avoid subjecting some (controversial) nominees to a Senate vote. Most recently, congressional gridlock over congressional appointments has often tempted President Obama to make more recess appointments.

Despite the importance of recess appointments to the functioning of the federal government, the text of the Constitution itself provides little elaboration on the scope of the recess-appointments power, stating simply that “[t]he President shall have Power to fill up all Vacancies that may happen during the Recess of the Senate, by granting Commissions which shall expire at the End of their next Session.” Notably, no further explanation is provided regarding what a “recess” is or what it means for a vacancy to “happen during” a recess.

Perhaps unsurprisingly, these are precisely the points of disagreement between the parties in Noel Canning. One side—Noel Canning, a company challenging a number of President Obama’s recess appointments to the National Labor Relations Board—argues that “recess” refers only to the time between official sessions of Congress, not adjournments within an official session, and that the recess-appointments power applies only to positions that become vacant during a recess, not to all positions that happen to be vacant during a recess. The Obama Administration, defending its appointments to the NLRB, has taken the opposite view on both of these points.

After Senate Majority Leader Harry Reid used the so-called “nuclear option” to change the Senate’s rules governing presidential appointments, the particular issue itself is somewhat academic. However, Reid’s action did not resolve the issue of who, ultimately, has the right to determine the answers to these questions.

Until now, the answer has been, emphatically, not the Court. Indeed, for many years, the president and the Senate have operated under a mutual understanding that any adjournment of the Senate longer than three days (the Senate sometimes adjourns early for three-day weekends) would constitute a recess, and that the recess-appointments power would extend to any position that happened to be vacant during such a recess. This compromise allowed the president to appoint some nominees without Senate approval if he was willing to wait until a recess, and it allowed the Senate to block particularly objectionable recess appointments by holding so-called pro forma sessions of the Senate—whereby a single senator would open the Senate for business and then promptly adjourn every three days to avoid the occurrence of a recess.

In Noel Canning, however, all of this seems likely to change. At oral argument, most of the justices seemed convinced that the text of the Constitution failed to support but indeed belied the compromise understanding of the recess-appointments power, thrusting the second-order question into the fore. As Justice Scalia asked the Obama Administration’s lawyer: “What do you do when there is a practice that…flatly contradicts a clear text of the Constitution?… [W]hich of the two prevails?”

With the necessity of recess appointments having been obviated by the Senate’s recent changes to the filibuster rules, how the Court thinks about this question, and more generally, the roles of the various branches in determining constitutional questions, may well be the most important part of its decision. The Court declared in its very infancy that “it is emphatically the province and duty of the judicial department to say what the law is.” But how far that authority extends within the halls of Congress itself is another question entirely.

Thomas Fu and David Friedman are the managing editors of the Stanford Law Review. Contact them at [email protected] and [email protected].