White House Counsel Pat Cipollone sent an eight-page-long middle finger to House Democratic leaders on Tuesday, pledging resistance to the impeachment inquiry into President Trump.

As a legal matter, Cipollone’s letter is nonsense. Several court decisions make it clear that the White House is not above the law. Executive privilege is real, and it sometimes prevents some inquiries into presidential behavior, but it is not an absolute privilege — especially in the context of a criminal investigation.

As a practical matter, however, Trump is likely to get away with it because there’s no one who can stop him. House investigators and others may be able to obtain a court order requiring the White House to comply with an investigation. But if Trump continues to refuse, Congress and the courts have limited options.

As Alexander Hamilton once wrote of courts: the judiciary “may truly be said to have neither FORCE nor WILL, but merely judgment; and must ultimately depend upon the aid of the executive arm even for the efficacy of its judgments.”

The constitutional mechanism, meanwhile, for dealing with a lawless president — impeachment and conviction — requires at least 20 Republican senators to vote to remove a president of their own party.

So long as Trump believes that his fellow partisans will hang together, he has little incentive to comply with a court order.

The question of how to define a “constitutional crisis” is hotly contested among scholars. Yet one common definition, according to Georgetown law professor Victoria Nourse, is “a fight among branches of government in which neither side backs down, and there is no clear resolution within the constitutional system.”

There is no resolution to the present crisis within our constitutional system. The White House announced its clear intention to violate the law. But the only sure mechanism to enforce that law, impeachment, is a paper tiger so long as Republican senators stand with Trump.

The law does not permit Trump’s extraordinary resistance to investigations

Cipollone’s letter reads less like a legal document than it does like a Sean Hannity monologue. But he appears to be arguing that the Trump administration is free to defy congressional subpoenas because the House impeachment inquiry has not given Trump “constitutionally mandated due process” that he believes he is entitled to.

Trump’s legal position appears to be that no one in his administration is under any obligation to cooperate with anyone investigating whether Trump violated the law: he has made such sweeping claims of immunity to investigation that a federal judge recently described his arguments as “repugnant to the nation’s governmental structure and constitutional values.”

Let’s take these two arguments in turn: the argument that Trump may demand that the House impeachment inquiry be conducted in a certain way and the argument that Trump has broad authority to resist investigations.

Cipollone claims that the House’s impeachment inquiry should afford Trump certain rights typically associated with criminal trials, including “the right to cross-examine witnesses, to call witnesses” and “to have counsel present.” But this demand misunderstands the role of the House during impeachment.

As Hamilton explained in the Federalist Papers, the House stands in the role of “accusers” during the impeachment process while the Senate acts as “judges” over anyone impeached by the House. A House impeachment inquiry is not, in other words, analogous to a trial. It is more similar to a police investigation of someone suspected of committing a crime.

Even at a Senate trial, an impeached official may not demand the kind of due process rights that Trump seeks. A similar issue arose in Nixon v. United States (1992), a Supreme Court case involving disgraced federal Judge Walter Nixon, who claimed that his impeachment trial did not afford him due process because certain parts of that trial were delegated to a committee consisting of only a subset of the Senate.

As the Court explained, the Constitution gives the House the “sole” power to impeach and the Senate the “sole” power to try those impeachments. The Supreme Court concluded that courts have virtually no authority whatsoever to second-guess the process Congress uses during an impeachment.

The executive branch has a very limited ability to resist subpoenas emerging from an impeachment inquiry

While the courts may not micromanage the process used during impeachment, they often have an obligation to enforce subpoenas. That was the holding of United States v. Nixon (1974), an entirely different Nixon case involving then-President Richard Nixon. This was the pivotal Watergate case that required Nixon to release incriminating tapes, which eventually led to his resignation.

This Nixon case concluded that many of a president’s communications with his aides are shielded from investigators. “Human experience teaches that those who expect public dissemination of their remarks may well temper candor with a concern for appearances and for their own interests to the detriment of the decisionmaking process,” the Court explained. To ensure that presidents receive honest advice from their advisers — even when that advice is unpopular or impolitic — courts should show “great deference” to a president’s assertion that internal White House communications should be kept secret.

This deference, though, is not absolute. Allowing the president to “withhold evidence that is demonstrably relevant in a criminal trial would cut deeply into the guarantee of due process of law and gravely impair the basic function of the courts,” the Supreme Court concluded, forcing President Nixon to turn over incriminating tapes that eventually led to his resignation.

A 1997 federal appeals court decision, In re: Sealed Case, offered a fuller explanation of executive privilege, defining it as coming in two different forms. The stronger form, known as the “presidential communications privilege,” applies to communications directly with the president, or communications “authored or solicited and received by those members of an immediate White House adviser’s staff who have broad and significant responsibility for investigating and formulating the advice to be given the President on the particular matter to which the communications relate.”

This privilege is what was at issue in the 1974 Nixon case. And Sealed Case described several limitations on it: Among other things, it is “limited to communications ‘in performance of [a President’s] responsibilities,’ ‘of his office,’ and made ‘in the process of shaping policies and making decisions.’” Sealed Case also suggests that congressional committees may breach the presidential communications privilege when it seeks information that is “demonstrably critical to the responsible fulfillment of the Committee’s functions.”

Meanwhile, a weaker privilege known as the “deliberative process privilege” permits “the government to withhold documents and other materials that would reveal ‘advisory opinions, recommendations and deliberations comprising part of a process by which governmental decisions and policies are formulated.’” But this privilege is extraordinarily weak. Indeed, it “disappears altogether when there is any reason to believe government misconduct occurred.”

So House investigators have broad power to subpoena almost all executive branch communications so long as there is “reason to believe government misconduct occurred.” They have somewhat less power to seek communications involving Trump and his inner circle, but even these communications may be subpoenaed when they will reveal information that is “demonstrably critical” to the impeachment inquiry. And documents unrelated to Trump’s official duties — such as, say, his tax returns — are not subject to executive privilege at all.

The White House’s sweeping refusal to cooperate with the impeachment inquiry simply has no basis in law.

What happens if the Supreme Court orders Trump to comply with the law and he says “no”?

If a court does order the administration to comply with congressional subpoenas, Trump’s first line of defense is the fact that Republican appointees control the Supreme Court. There’s no guarantee than any such order will be upheld by this Supreme Court, no matter how clearly existing caselaw says that it should.

But let’s assume the best-case scenario for impeachment investigators. Suppose that the courts move swiftly, that they soundly reject Trump’s defiance of congressional oversight, and that the Supreme Court orders Trump to end that defiance. What comes next if Trump refuses to comply with that order?

I asked Josh Chafetz, a Cornell law professor and author of Congress’s Constitution: Legislative Authority and the Separation of Powers, what legal options exist shy of impeachment. His response was pretty fatalistic. “At the point at which we’re talking about ignoring court orders,” Chafetz told me, “what does ‘legal options’ even mean any more?”

The remedy, if it came at all, would have to be political. If Trump were to defy both the House and the judiciary, Chafetz predicts that the president “would outrage a decent chunk of the public” and that Trump’s approval rating would crater. That “would have the effect of turning a bunch of GOP elites against him, which, in turn, might drive his approval still lower. I think at that point it ends with his ouster.”

But Chafetz adds that he’s not especially certain of this outcome and he “could very easily see it going other ways, too.”

Trump presides over a Republican Party that is both more united and more homogenous than the party Nixon presided over. Even if President Nixon wanted to defy the 1974 Nixon decision, it’s unlikely he could have gotten away with such a decision because much of his own party would have turned against him.

For one thing, political parties were far less “sorted” in 1974 than they are today. There were still conservative Democrats and liberal Republicans and these factions wielded considerable power within their party coalitions. After Nixon left office, for example, Republican President Gerald Ford picked the leader of his party’s liberal wing as vice president.

So lawmakers in 1974 were accustomed to working across party lines because that was often the only way to find enough ideological allies to get a bill through Congress. Today’s lawmakers are far less accustomed to forming such cross-partisan alliances.

Similarly, for reasons that Princeton political scientist Frances Lee explains, Nixon-era Republicans had a particular incentive to work with Democrats that Trump-era Republicans do not. For most of the 1970s, largely due to the fact that many Southern conservatives still identified as Democrats, the Democratic Party had an enormous advantage in the battle for control of Congress. Because Republicans expected to be in the minority, they had a strong incentive to make nice with Democrats because forming bipartisan alliances was the most reliable way for Republicans to wield power.

Lee’s thesis is that when “neither party perceives itself as a permanent majority or permanent minority,” the parties tend to polarize. Why cooperate with your partisan rivals when you can undermine them and increase your own chances of gaining the majority in the process?

Republicans have a strong incentive to stick with Trump no matter how often Trump thumbs his nose at the law. Republicans don’t see Democrats as potential allies; they see them as bitter rivals trying to take something they want.

Many of the Founding Fathers, for what it’s worth, understood the risk of such a polarized system and hoped to avoid it. “There is nothing I dread So much, as a Division of the Republick into two great Parties,” future President John Adams wrote in 1780. A two-party system “is to be dreaded as the greatest political Evil, under our Constitution.”

Yet many of the men who designed the Constitution believed that they’d built a system that was immune to partisanship. The “well constructed Union” envisioned under that Constitution, future President James Madison wrote in the Federalist Papers, would have a “tendency to break and control the violence of faction.”

It didn’t. As anyone familiar with the musical Hamilton can tell you, the nation’s leaders split into two political parties almost immediately after the Constitution was ratified.

The framers, in other words, built our government on the assumption that lawmakers could rally together during times of crisis, rather than dividing into teams and digging in for partisan advantage. Polarized political parties simply are not compatible with a system that requires two-thirds of the Senate to remove a president — at least, if you don’t want a system where the president is immune from impeachment.

That’s likely to leave the question of whether Trump will face consequences for lawless behavior to the voters — which is ultimately where it rests in any democracy. A well-designed constitution can mitigate the risk that a corrupt executive will hold onto power but it can’t prevent the voters from repeatedly electing such a leader.

As Chafetz warns, “no constitution on its own can prevent power holders from blowing through it if there is not sufficient political will to stop them.”