This week, President Trump will announce his nominee to replace Justice Anthony Kennedy on the United States Supreme Court. Senate Majority Leader Mitch McConnell (R-Ky.) has promised to schedule the nominee's confirmation hearings for this fall, before the midterm elections.

If and when McConnell carries through on this promise, Senate Democrats should immediately file a federal lawsuit against him for violating the so-called McConnell Rule. (According to this rule, as McConnell himself stated on Feb. 13, 2016, "The American people should have a voice in the selection of their next Supreme Court Justice.") The issue - whether the McConnell Rule is now binding precedent - would not be political (and therefore "nonjusticiable") but rather fundamentally legal (and therefore "justiciable").

The minority party needs to have some remedy, some legal recourse, when the majority leader is completely immune to considerations of fairness and consistency in his exercise of the Senate's substantial constitutional powers. Imagine, for example, that McConnell suddenly stipulated that only 40 instead of 51 votes were necessary to confirm a Supreme Court nominee. Clearly, the validity of this rule change would be a constitutional question, rather than a political question, because it implicates a fundamental democratic principle: majority rule.

McConnell's imminent abandonment of the McConnell Rule implicates an equally fundamental democratic principle: due process for 49 percent of the Senate, which itself represents tens of millions of American citizens. Just as the judiciary would have the authority to intervene if McConnell changed the vote threshold from 51 to 40 (or, for that matter, if he refused to step aside as majority leader should the Democrats regain control of the Senate in November), so, too, the judiciary has the authority to intervene if McConnell violates his McConnell Rule.

Assuming that a court - preferably the Supreme Court - agrees with my analysis, McConnell (the defendant) would then have to argue either that the McConnell Rule is not law or that it is law but, as he claimed on June 28, applies only to "constitutionally lame-duck" presidents. Either way, however, he would lose.

Whether McConnell likes it or not, the McConnell Rule is law. When McConnell declared in 2016 that Supreme Court nominees are not allowed hearings in an election year, that decree carried legal force - the same legal force as former Senate Majority Leader Harry Reid's (D-Nev.) reduction of the threshold to defeat filibusters for executive appointments and most judicial nominations from 60 to 51 senators.

As every lawyer knows, not all laws are statutes. Many laws come in different forms: court decisions, agency rules, general principles, customary practices and sometimes even widely accepted opinions by legal experts. Like these non-statutory propositions, parliamentary rules announced by Senate majority leaders constitute laws as well. As a result, they are binding on future legislators unless and until they are explicitly overturned.

Importantly, if McConnell still were to maintain that the McConnell Rule is not law, then the so-called Biden Rule was not law either. But if the Biden Rule was not law, then McConnell's claim on March 16, 2016, to be bound by it - "The Senate will continue to observe the Biden Rule so that the American people have a voice in this momentous decision" - was a lie so monumental that the entire process by which Justice Neil Gorsuch ascended to the high court would have to be deemed constitutionally invalid and, therefore, subject to retraction. This is obviously too great a cost for McConnell to risk.

McConnell's only real option, then, is to concede that the McConnell Rule is law and then argue, as he did on June 28, that it applies only to "constitutionally lame-duck" presidents. But there are three problems with this argument.

First, once again, McConnell in 2016 tried justifying the McConnell Rule by arguing that it really reduced to the Biden Rule. When Biden announced the supposed Biden Rule (on June 25, 1992), however, President George H.W. Bush was not a lame duck but, rather, a first-term president running for reelection. The McConnell Rule, then, must apply in the context of a first-term president as well.

Second, President Obama was not a lame duck when McConnell announced the McConnell Rule in mid-February 2016. On the contrary, he had 11 months remaining in his term, which is nine more than what is normally considered to be a lame-duck period.

Third, even if we concede that 11 months left in a presidency somehow constitutes a lame-duck period, then four months left for the current Senate certainly constitutes a lame-duck period. And it would be entirely arbitrary and unjustifiable to apply the McConnell Rule only to lame-duck presidents and not to lame-duck Senates.

Like the rest of the judiciary, the Supreme Court is supposed to be above politics, a nonpartisan check on the other two branches. So when McConnell officially schedules confirmation hearings for Trump's nominee, Senate Democrats need to do more than complain. They need to take him to court. And the court needs to tell McConnell, at long last, that his power extends only to facilitating the Senate's advice and consent role, not to forcibly converting the judiciary into a mere extension of the Republican Party.

Ken Levy is the Holt B. Harrison Professor of Law at Louisiana State University's Paul M. Hebert Law Center. Follow him on Twitter @tardigrade18.