After almost 231 years of scrutiny, it’s hard to imagine there’s much left in the U.S. Constitution that hasn’t been fully explored. But the special counsel’s probe into Russia’s interference in the 2016 election, and whether anyone from Donald Trump’s presidential campaign cooperated with that nation, is raising major legal questions that this country has rarely, if ever, faced.

Many questions involve the scope and limits, if any, on the chief executive’s powers. President Trump and his legal supporters have argued publicly that the leader cannot be subpoenaed or indicted while in office; that a president can start or shut down any federal investigation, including one into her or his own conduct; and that a president may pardon anyone for any reason anytime, even himself or herself. The Russia investigation has cast a light on apparent gaps in the Constitution, including such quandaries as what happens if a president ignores a Supreme Court order, or what check is available for a Congress that abdicates its watchdog role over the executive branch.

To gain a better understanding of some of the issues increasingly in play, the Gazette interviewed Mark Tushnet, Michael Klarman, Steven Levitsky, and Steven Jarding, Harvard faculty members who have expertise in constitutional law and legal history, democratic and authoritarian governments, and American politics. Here’s what they had to say.

GAZETTE: Our system of checks and balances has worked largely as planned for the last 230 years. But now it appears that the president is eager to test the limits of executive power. Because past presidents largely abided by not just the office’s constitutionally mandated boundaries but by generally accepted norms of conduct, did we perhaps overestimate the framers’ foresight to head off a leader apparently intent on challenging the idea of co-equal branches of government? If yes, what did they get wrong, and what could fix it?

MARK TUSHNET (’67, WILLIAM NELSON CROMWELL PROFESSOR OF LAW AT HARVARD LAW SCHOOL): The Constitution was designed to do a reasonably good job of filtering out demagogues and other “unfit” characters from high office. But the Founders knew that the filtering process would be imperfect and that sometimes people of unfit character could rise to the top. Their remedy was the separation-of-powers system, in which the self-interest of people in each branch would lead them to oppose overreaching by someone in the others. They knew of the possibility that political parties would develop, but they thought their design would discourage them. (This was especially true of the design of the Electoral College, which was expected to generate local and regional “favorite sons,” from among whom the House would pick.) But nationally organized political parties developed rather quickly after the national Constitution took effect. Still, for a long while the parties were coalitions of locally based parties, and cross-party alliances could occur.

The novel development, over the past generation or so, is of highly polarized and internally unified parties, which leads party members to act in the service of their party — to defend an overreaching president of their party, for example. There are few obvious structural “fixes” for this problem. Electing the president by national popular majority vote might help, as might various forms of shifting away from elections in which the winner is the person with a plurality of the votes (single-transferable voting, and other devices). But, mostly the remedy lies with political leaders putting forth programs that will persuade voters that we should abandon our current polarized positions.

MICHAEL KLARMAN (KIRKLAND & ELLIS PROFESSOR OF LAW AT HARVARD LAW SCHOOL): As James Madison famously explained in the Federalist No. 51, the practical efficacy of the Constitution’s system of separated powers and checks and balances depends on the assumption that the government’s various institutional actors will have personal incentives to constrain one another’s power (ambition counteracting ambition, as Madison put it). That assumption, however, was grounded in a political context in which political parties did not exist. The rapid development of such parties in the 1790s ensured that the system would not operate precisely as the Founders had anticipated. Specifically, when the president and the majority of the House and Senate come from the same political party, those branches of the national government are more likely to act in tandem than in opposition to one another.

That said, throughout American history, members of Congress hailing from the same party as the president have proved at least occasionally willing to check executive authority. Perhaps most famously, many Republicans (though not a majority on the House Judiciary Committee) supported the impeachment of Republican President Richard Nixon during the Watergate scandal. Today, by contrast, Republican congressional representatives and senators have been “utterly supine” (to quote retiring Arizona Sen. Jeff Flake) in their stance toward President Trump’s transgressions of constitutional rules and norms.

Three factors explain why President Nixon could have been impeached in 1974, while President Trump probably cannot be today. First, Democrats dominated both houses of Congress then, while Republicans control both houses today. Second, in the 1970s the two major political parties were ideologically diverse. Conservative Democrats and liberal Republicans, plentiful in the early 1970s, barely exist in Congress today. The most conservative congressional Democrat in 2018 is more liberal than the most liberal Republican. Third, there was no analogue in 1974 to today’s Fox News, which has become essentially a propaganda arm of the Trump administration, performing a function similar to that of government-controlled media in increasingly authoritarian Poland and Hungary — stating untruths, spinning conspiracy theories, and diverting attention from the administration’s malfeasances.

In 1974, most Americans got their facts — and they were facts — from Walter Cronkite, Huntley and Brinkley, or Howard K. Smith. But facts are increasingly out of fashion today. According to opinion polls, a majority of Republicans believe (still) that President Obama was not born in the U.S., that human-caused global climate change is not real, and that Trump would have won the popular vote in the 2016 presidential election had it not been for the illegal ballots cast by 3 to 5 million undocumented immigrants. In the absence of consensus about basic facts, impeachment is not a realistic possibility because not enough Republicans will believe any facts uncovered by Special Counsel Robert Mueller with regard to the Trump campaign’s collusion with Russia or the president’s possible obstruction of that investigation.

Essentially unchecked by a Republican-controlled Congress, Trump has proved willing to push the limits of both constitutional rules and historically grounded norms of the presidency. The president’s continued ownership of the Trump Organization amounts to an almost daily violation of the Constitution’s Foreign Emoluments Clause. Trump’s successful intimidation of National Football League team owners to suppress their players’ protests against racial injustice by kneeling during the playing of the national anthem quite possibly violates the First Amendment’s protection of freedom of speech. So does Trump’s repeated efforts to bully the postmaster general into raising package-delivery rates for Amazon, which is a brazen attempt to retaliate against its CEO, Jeff Bezos, for negative coverage of the administration by The Washington Post, which Bezos independently owns.

A Congress controlled by Republican majorities has done almost nothing to check the president’s transgressive behavior. Instead of defending the special counsel’s investigation, Senate Majority Leader Mitch McConnell has blocked a proposed bill to protect Mueller’s independence in the face of Trump’s repeated threats to fire him. (McConnell’s peculiar logic is that Mueller doesn’t require protection because the president hasn’t tried to fire him yet, though we now know that Trump twice sought to do precisely that.)

House Republicans have been even more complicit with the Trump administration. With the active connivance of Speaker Paul Ryan, the chair of the House Intelligence Committee, Devin Nunes, has repeatedly endeavored to delegitimize the special counsel’s investigation, even to the point of dangerously undermining public confidence in the FBI and the Justice Department. Nunes has fabricated stories about the unauthorized “unmasking” by the Obama Justice Department of American citizens whose words were inadvertently captured on lawful wiretaps, improper national security surveillance of Trump campaign aide Carter Page … and the FBI’s planting of “spies” within the Trump campaign. House Freedom Caucus leaders Mark Meadows and Jim Jordan have threatened to launch impeachment proceedings against Deputy Attorney General Rod Rosenstein for refusing to turn over to Congress Justice Department materials, when doing so may jeopardize the Mueller investigation. One could imagine congressional Republicans’ resuming traditional oversight functions were Trump’s approval ratings within the party to decline from their near-record levels of 85 to 90 percent. Yet it is not clear what additional transgressions by Trump would be necessary to produce that effect.

Federal courts have done a better job than Congress thus far of curbing the administration’s unconstitutional actions. Numerous lower courts have struck down the thinly veiled Muslim travel ban, the executive order banning openly transgender individuals from military service, and the executive order threatening “sanctuary cities” with a loss of federal law-enforcement funding.

For three reasons, however, judicial checks on this president are unlikely to prove very significant in the long term. First, the Supreme Court, which has a 5‒4 conservative majority, is unlikely to prove a robust check on a Republican president. Republican justices have already demonstrated in recent years that they think roughly the same way as Republican politicians about voter I.D. laws, state voter purges, the importance of a key provision of the 1965 Voting Rights Act, and the termination of manual vote recounts in presidential elections that potentially threaten the ascension of a Republican candidate to the presidency. They may well feel the same way as Republican politicians about Trump’s assault upon the norms and constitutional rules of democracy.

Second, the lower federal courts currently lean strongly Democratic (because, prior to 2016, Democratic presidents were responsible for nominating federal judges for 16 of the previous 24 years), but that will not be the case much longer. Trump has already appointed more than 10 percent of the federal appeals court judges in the nation, as Senate Republicans have confirmed Trump’s judicial nominations at a record pace. Third and finally, the Supreme Court throughout American history has rarely proved a strong check on executive malfeasance during time of war or terror. The court’s acquiescence in Japanese-American internment during World War II is only one of many illustrations of this point.

TUSHNET: This is a very controversial question, and the best answer really is that no one can offer a completely slam-dunk argument either for or against the proposition that the president cannot be criminally prosecuted while in office. My own view, for what it’s worth (not much), is that the balance of the arguments tilts slightly against that proposition.

KLARMAN: Scholars disagree about whether the Constitution permits criminal prosecution of a sitting president. The document explicitly contemplates removal of the president through an impeachment by the House of Representatives, followed by a judgment of conviction from the Senate (with a two-thirds majority of the senators present during the trial being required for removal). The Constitution further provides that “the party convicted shall nevertheless be liable and subject to Indictment, Trial, Judgment and Punishment, according to Law.”

The qualifying clause in this provision is susceptible to two interpretations. Those who reject criminal prosecution of a sitting president argue that the negative inference of expressly authorizing criminal prosecution of a president once removed from office through conviction on an impeachment is that the president may not be criminally prosecuted before being removed from office. An alternative reading is that the qualifying clause simply forecloses any possible “double jeopardy” objection to criminally prosecuting a president who has already been tried and convicted on an impeachment. On this view, the clause says nothing about whether a sitting president can be criminally prosecuted.

Neither side of this debate limits itself to arguments based on the constitutional text. Those who reject criminal prosecution of a sitting president rely equally on the policy argument that because the executive power of the U.S. is vested in a single individual (the president), governance of the nation would be effectively crippled were he to be jailed during his tenure in office. Those on the other side of the debate argue that the vice president could easily assume the duties of the president while incarcerated. They also argue that the Constitution’s impeachment clauses do not distinguish among various civil officers of the U.S., and historical precedent plainly permits criminal prosecution of other sitting civil officers, including the vice president (as evidenced by the indictment of Vice President Spiro Agnew for tax evasion in 1973).

On two occasions (in 1973 and 2000), the Office of Legal Counsel, which provides legal guidance to the executive branch of the federal government, has opined that a sitting president cannot be criminally prosecuted. However, also on two occasions, the legal staff of independent counsels (Leon Jaworski in 1974 and Ken Starr in 1998) concluded the opposite. Most legal scholars would probably be surprised if Robert Mueller were to pursue an indictment against President Trump.

GAZETTE: How would a court, even the Supreme Court, enforce an order over a president if he or she were to simply ignore it? If the court could not enforce an order, then what?

TUSHNET: One can come up with scenarios in which the court’s orders might be coercively enforced (U.S. marshals might take their orders from the court rather than president, for example, and — in the ultimate stage — U.S. military troops might refuse to comply with a presidential order). But if things get to that point, the political atmosphere will have become so heated that, really, no one can say how things would turn out.

KLARMAN: Court rulings make little practical difference unless they are enforced. President Dwight D. Eisenhower’s initial unwillingness to enforce Brown v. Board of Education in the face of Southern white resistance — and his subsequent reluctance to go beyond a lukewarm endorsement of the ruling as the law of the land — was one of the principal reasons that so little school desegregation took place in the South in the decade after 1954. The president has the military at his disposal. The Supreme Court does not.

For that same reason, the president is likely to win most confrontations with the federal courts. President Abraham Lincoln successfully defied Chief Justice Roger Taney’s order invalidating the president’s suspension of the writ of habeas corpus during the Civil War. While President Andrew Jackson probably never uttered the infamous words, “[Chief Justice] John Marshall has made his decision; now let him enforce it,” the sentiment expressed in those words is accurate. The court’s decision in 1832 invalidating the state of Georgia’s assertion of sovereignty over the Cherokee Nation could not have been effective without the president’s backing. When the Supreme Court invalidated several New Deal measures in 1935‒36, President Franklin D. Roosevelt threatened to [expand and] pack the court, and the justices quickly backed down from the confrontation.

Trump might well choose to disregard an inconvenient judicial ruling were he to calculate that he could get away with doing so. During his business career, Trump frequently breached legal obligations — such as paying subcontractors or creditors what they were due — until compelled by a court to comply with them. Yet courts have no mechanism for coercing a recalcitrant president.

So why did President Nixon ultimately turn over the Watergate tapes, rather than defying the Supreme Court’s order that he do so? Nixon had record-low approval ratings in August of 1974, and the House Judiciary Committee was on the verge of returning articles of impeachment against him. As already noted in response to question 1, three important differences between then and now bear on Trump’s ability to get away with violating a hypothetical court order: Republicans currently control Congress; polarization among the political parties is greater than at any time since the Civil War; and the proliferation over the last 30 years of right-wing media outlets has deprived political adversaries of a common set of facts.

Trump has already denounced as a “so-called judge” the first federal jurist who invalidated his Muslim travel ban, as well as labeling “a disgrace” the panel of appellate judges who were about to affirm that ruling. It is not clear that Republican office holders, who have barely protested the president’s fact-free denunciations of the F.B.I. and his own Justice Department, would challenge his defiance of an inconvenient judicial order.

GAZETTE: The executive branch enjoys wide latitude in a number of critical areas in which the only restraint from overreach or an abuse of power is a president’s willingness to abide by accepted norms. Trump’s presidency has highlighted that the Constitution does not address or provide a structural check or limit a president in key realms. (The accompanying chart provides examples.)

Because there are so many gray areas about the outer contours of presidential power in the Constitution, and Congress currently appears unwilling to order compliance or penalize noncompliance to established norms, what does that mean for the country? Is it on a dangerous path, or is that overstated? Are there remedies to prevent or stop potential damage in these areas?

STEVEN LEVITSKY (PROFESSOR OF GOVERNMENT AT HARVARD UNIVERSITY AND CO-AUTHOR OF “HOW DEMOCRACIES DIE”): Every constitution, every formal set of rules has gray areas. It’s impossible to write a constitution without any gray areas. Every rule has ambiguities; every rule is open to interpretation. But the U.S. Constitution is a remarkably short, and in many instances vague, document. Compared with other constitutions, it really does not specify a number of things, including, as you note, limitations on presidential power. So one thing that often happens is when we rely on the norm of forbearance, meaning a self-conscious effort to underutilize power, not to use the letter of the law in ways that clearly violate the spirit, we rely on self-restraint until the rule gets abused. And once the rule gets abused, you replace the norm with a written rule. You correct it by changing the rule.

One example of that historically in the U.S. is two-term presidential limits. For a century and a half, there were no constitutional term limits to the president. We relied on this entirely informal norm, established precedent set by George Washington that the president only stays two terms. Once that gets violated by Franklin Roosevelt, then they’ve got to write it into the Constitution. And I think there’s a good chance that you’ll see a fair amount of that. In fact, there’s already talk of it, post-Trump. You do a good job of listing a bunch of gray areas that Trump is clearly threatening to trample upon. So, there’s this area of conflict of interest where we relied on presidents to not obviously make money out of the presidency, and most presidents have been pretty good about that, so we didn’t have to worry about writing it into the rules because presidents restrained themselves. Trump has not restrained himself.

I would not be surprised to see efforts, post-Trump, to tighten those rules, to write down what for many years had been informal. That same thing could happen with presidential-pardon powers. There have been very, very few cases where presidents have abused this almost unlimited authority to pardon to benefit their political team or their political inner circle or themselves. And Trump is clearly threatening to do that. He’s already used it in a fairly politicized way. If he abuses his pardon power, I think you’ll see real discussion after his presidency about adding greater restrictions on presidential power to pardon. There’s already an effort by Christine Todd Whitman and some others to formalize a bunch of things in the law in terms of constraining the presidency.

When we have a president who is clearly not committed to basic constitutional norms and even basic civil liberties, who’s willing to abuse power and, at the same time, both houses of Congress are controlled by a party that has abandoned all efforts of oversight, there’s a lot to worry about. Now, this is not Hungary or Turkey, or certainly not Russia. There are a lot of factors working in defense of American democracy as well. Many of our institutions continue to work pretty well, including the media, the judiciary, federalism, and elections. And so, one way out of this is for the opposition party to win control of one or both houses of Congress. If the Democrats win Congress, the constraints on Trump will be greater, the oversight will be much greater. If the Republicans retain control of both houses in 2018 and if they win in 2020 — and both of those outcomes are entirely possible — I think we’re in a more dangerous scenario. Does that mean we’re heading toward Russia? Probably not. Eighteen to 24 months of abuse of that oversight is one thing; four years, six years, eight years of abuse of that oversight and the ability to slowly pack the different state agencies and pack the judiciary can be much more damaging in the long run. I don’t think fascism is around the corner. I don’t think we’re headed toward outright dictatorship. But the longer you’ve got a president with authoritarian instincts in the White House, and a completely disciplined, loyal party in control of both houses of Congress, it’s a dangerous situation.

STEVEN JARDING (LECTURER IN PUBLIC POLICY AT HARVARD KENNEDY SCHOOL WHO TEACHES THE POPULAR “MAKING OF A POLITICIAN” COURSE): Traditionally, U.S. presidents have been given wide latitude from overreach by Congress or other governmental entities because it has been accepted doctrine that U.S. presidents hold a modicum of respect for the institution and hold themselves to a standard that would surpass minimum expectations for executive leadership. Donald Trump has failed both tests. But also, he is not the only person with dirty hands here. There is an expectation that Congress — even members of the same party as a sitting president — will serve as a watchdog over questionable practices of a president, and this Congress has abdicated this critical responsibility. Because of Trump’s arrogant attitude toward his own power and because his own congressional party leaders refuse to hold him to traditional and important standards, he flouts rules against using his position for personal financial gain for him and his family, he refuses to release his tax returns or medical records, he offers mixed and often contradictory explanations of his personal dealings with foreign entities — a particularly dubious and disturbing pattern in light of his apparent business ties with nefarious Russian business operatives while he turns a blind eye toward Russian interference in the 2016 U.S. elections — the list goes on and on.

Sadly, while I believe the Constitution provides a check on abuses of presidential powers, if Congress renders itself neutered to hold a president accountable, constitutional direction means little. Without a president who respects our culture and history with regard to his own personal actions in office, or Congress filling its critical oversight function, there is little that can be done short of stand-alone investigations, such as we are seeing with the Mueller investigation, or by the American public changing congressional and executive leaders.

GAZETTE: Was it a flaw that the Constitution does not appear to constrain a president’s pardon power or require him or her to follow any procedural review to ensure a pardon is not granted for a corrupt purpose?

TUSHNET: No, it’s not a design flaw. We want the pardon power to be completely discretionary so that presidents can address flaws in the criminal justice system that couldn’t be seen in advance, including improper exercises of discretion by prior prosecutors and judges. We would ordinarily want some sort of processes prior to issuing a pardon, but we also should want the president sometimes to ignore those processes. The real problem goes back to the initial question: The overall system’s operation often depends on the assumption that a president will not act too far outside the bounds of ordinary prudence.

KLARMAN: All powers can be abused, as the Constitution’s defenders repeatedly noted in 1787‒88 in response to their adversaries’ vivid hypotheticals conjuring potential abuses of the national government’s newly granted powers.

Opponents of the Constitution’s ratification protested the breadth of this pardon power. Specifically, they worried that a president might pardon co-conspirators in a scheme to commit treason against the nation. When George Mason raised precisely this objection to the Constitution at the Virginia ratifying convention, James Madison — who played a larger role than any other single individual in the drafting and ratification of the Constitution — responded that while such a presidential pardon would be legally effective, it would also constitute adequate grounds for impeachment.

Trump’s pardons thus far are legally effective, no matter how transgressive of traditional legal norms, rule-of-law values, and Justice Department procedures they may be. Yet, as Madison explained, a presidential pardon may be both legally effective and adequate grounds for an impeachment if shown to be part of a scheme to obstruct justice. Trump’s recent claim that he has the “absolute” power to pardon himself is more tendentious. As is often the case, the text of the Constitution does not definitively answer this question. The main argument that a president can pardon himself is that Article II does not say that he cannot.

The principal arguments to the contrary are threefold. First, the word pardon derives from the same root as the Latin term for donate, and one cannot conventionally be said to donate something to oneself. Second, an ancient legal maxim, well-known to the Framers, is that no one may be a judge in his or her own case. A self-pardon would flout that norm. For precisely this reason, the Office of Legal Counsel concluded in 1974 that President Nixon lacked the authority to pardon himself, as he was apparently considering doing. Third, as the Constitution explicitly contemplates criminal prosecution of a president after his removal from office, the notion of a self-pardon makes little sense, since any president facing impeachment and the prospect of subsequent criminal prosecution would simply pardon himself.

Because Trump is unlikely to be indicted while in office or removed from office through impeachment, Democrats would be well-advised to focus their energies instead on constraining him to the greatest extent possible while he remains president, something that Republicans have evinced little enthusiasm for doing. In the end, only public opinion, as registered through elections, can constrain an autocratically inclined president.

This article appeared in the Harvard Gazette on July 19, 2018. These interviews have been edited by that publication for clarity and length.