Wally McNamee / Olivier Douliery / Chip Somodevilla / Getty / The Atlantic

This story was updated on January 27, 2020 at 11:00am.

The Senate impeachment trial of President Donald Trump is under way. Senators now face the monumental question of whether to remove the president from office—and yet, something bigger is at stake here. The Constitution’s fundamental design is on trial too.

This is clear from the articles of impeachment themselves. Start with the first article, which charges that the president abused his power by holding support for an ally foreign government hostage to better his chances at reelection, rather than advancing the interests of the United States.

But President Trump, with the support of his attorneys at the Department of Justice and his own White House counsel, has argued that he has absolute authority over foreign policy. Thus, no abuse of power is possible, because any power he exercises is legitimate by definition. His attorney Alan Dershowitz has told the public he will go so far as to argue that the Constitution does not even allow impeachment for abuse of power, only for crimes.

Trump’s defense is a direct test of the Constitution’s allocation of power when it comes to foreign policy. The Constitution distributes foreign-policy power between Congress and the executive branch. The president commands the armed forces and controls diplomacy through the State Department, but Congress raises and pays for the military, appropriates foreign aid, and has the sole power to declare war.

There are areas of tension and uncertainty the Constitution doesn’t address, and presidents of both parties have fought with Congress over their respective roles. But until Donald Trump, presidents have at least seen the relevance of congressional power. According to the historian Jon Meacham, George H. W. Bush mentioned impeachment five times in his personal diary as he labored for congressional approval to get Iraqi troops out of Kuwait after its invasion. If Congress wouldn’t approve, the elder Bush believed he might face impeachment if he moved forward regardless. Barack Obama spent six months striking ISIS in Iraq and Syria, but did go to Congress eventually to authorize military force. Bush the younger requested and received approval for military action from the Democratically controlled Senate in 2002. Nancy Pelosi refused to consider an impeachment investigation of George W. Bush for initiating the invasion of Iraq based on a misrepresentation that Iraq had weapons of mass destruction. But the point is, impeachment is Congress’s way of reining in a president who has over-assumed foreign-policy authority. In this way, the impeachment of Donald Trump tests whether doing so is possible, which is a test of the Constitution itself.

The second article of impeachment focuses on another core constitutional principle: congressional oversight of the executive. It, too, is a crucial test of the Constitution, not an esoteric argument about some generic allegation of wrongdoing. This article charges Trump with obstructing the impeachment process itself. Reports that former National Security Adviser John Bolton’s book manuscript contains evidence central to the inquiry but that has not yet been heard in a proper forum have only added to the gravity of what’s described in the second impeachment article.

Republicans have tragically endorsed Trump’s defiance of Congress’s every query. Remember that neither Richard Nixon nor Bill Clinton argued that he didn’t have to give Congress any documents, they certainly didn’t argue that they could block all witnesses in their impeachment investigations, and they didn’t get away with blocking evidence to the extent that they tried.

The fact that Republicans like Senator Lindsey Graham demanded witnesses during Clinton’s impeachment trial, and that every Senate impeachment trial has included witness testimony, has not deterred the Republicans who support Trump, even as they point to the Clinton trial as precedent. Clinton’s trial had excerpts of videotaped depositions of Clinton himself and Monica Lewinsky, but that is exactly the point. The witnesses had been deposed, evidence gathered, and the Senate saw it all. More important, the stakes were not as high. Here, the Constitution’s central organizing principle to protect the country against an authoritarian regime is on the line: the balance of powers among the three branches of government.

A real impeachment trial—one with all the evidence available, and senators who were intent on following their oaths, not their polls—would mean that the Senate would be forced to consider the limits of presidential power in a context of personal gain. Yet most Republicans have been so completely dismissive of the serious allegations against the president, they have reinforced the absolute authority of Trump in matters of national security. By refusing to consider calling Bolton, Acting Chief of Staff Mick Mulvaney, and their aides, Senate Republicans are suggesting that there is not even enough evidence to support getting more evidence.

Should they succeed, obstruction becomes a valid means to end congressional impeachment. The complete circularity of the Republican arguments would put the Constitution in an unbreakable bind. A future president could again refuse to turn documents over to Congress and could block all government witnesses, even if their testimony directly relates to crucial evidence around impeachable offenses. Then the president’s party can say that the evidence is insufficient to prove impeachable offenses.

As the constitutional scholar Michael Gerhardt testified during the December 4 House Judiciary Committee impeachment hearing, the president “says he is entitled not to comply with all subpoenas […] He’s immune to that. He’s entitled to keep all information confidential from Congress, doesn’t even have to give a reason. Well, when you put all those things together, he’s blocked out every way in which to hold himself accountable except for elections. And the critical thing to understand here is, that is precisely what he was trying to undermine in the Ukraine situation.” The paradox is paralyzing. It eviscerates not only the impeachment power but also the design of the branches put in place by the Founders to protect the country from becoming what they were trying to leave behind—monarchy.

Fundamentally, this impeachment is a test of the Constitution, which is another way of saying it is a test of how the American system allocates power. To condone the president’s behavior—and, unforgivably, to not even adequately investigate it—is to shift power further into the executive, to break the provisions for oversight that the Constitution created, and to take a major step toward the sort of consolidated power the Framers sought to avoid.

This story is part of the project “The Battle for the Constitution,” in partnership with the National Constitution Center.

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