Donald Trump's election has raised deep concerns, even among his supporters, that he may misuse the vast powers of the presidency. We believe that he can take early steps now, even before he takes office, to signal that he will use executive power to unify the country, despite a campaign that emphasized differences within the Republican Party and among American voters generally.

Trump should look for policy initiatives where he can appeal to both Republicans and Democrats. He will need Congress' support for tax cuts, regulatory reform, and a rejuvenated military. We believe he can make three commitments, well within the president's constitutional authorities, to show that he will use the office in the public interest and to respect democracy, rather than lean toward authoritarianism.

First: The president-elect should promise a pardon, on day one, for Hillary Clinton. Article II of the Constitution places no limit on the president's power to "grant reprieves and Pardons for Offences against the United States," except for impeachment. Many Americans believe Clinton was guilty of conduct that would trigger prosecution of a lesser figure. But an actual prosecution would create the terrible appearance of pursuing his political opponents with criminal law. A prosecution would divert attention from all other Trump initiatives and discourage any compromise and cooperation from Democrats.

Saving the country from bitter turmoil is one of the reasons why the president has a pardon power. In Federalist 74, Alexander Hamilton argued that the president should have the sole power to pardon to "restore the tranquility of the commonwealth." A pardon, however, would not just be a get-out-of-jail free card. It would signal that Clinton violated the law with her private email server and mishandling of classified information. Nor would a pardon bar the Justice Department from fully investigating any corruption involving the Clinton Foundation. A pardon would show that a President-elect Trump can win with grace, put the nastiness of the campaign behind us all, and focus our energies on the future.

Second: Trump should announce a nominee to fill the Supreme Court seat of Justice Antonin Scalia immediately. Under Article II of the Constitution, the president "shall nominate, and by and with the Advice and Consent of the Senate, shall appoint" the justices of the Supreme Court and all other lower federal court judges. Of course, Trump cannot make a formal nomination until he takes office. But presidents have long selected cabinet members before Inauguration Day. By committing to a nominee now, Trump can underscore the Constitution's importance to him and reassure the many who supported him solely for conservative control of the Supreme Court.

We hope that Trump will not compromise on a Supreme Court nomination in exchange for congressional support for high priority legislation - such as a big infrastructure bill. Trump can't be a successful president if he can't work with his own party in Congress. Most Republicans had already won their seats in Congress before Trump arrived on the scene. Some, such as Sen. Pat Toomey (R., Pa.), held their seats by keeping their distance. Trump's choice of a serious conservative would unify congressional Republicans - indeed all Republicans - behind him.

Trump could appeal to the center by selecting a nominee who could be easily confirmed. During the campaign, he took the unprecedented step of releasing names of "the kind" of nominees he would support, any of whom would make for a good justice. One stood out: Sen. Mike Lee (R., Utah), a deeply thoughtful conservative who served as a clerk for Justice Samuel Alito. As a sitting senator, he would be more easily confirmed. The Senate only once has rejected the nomination of a sitting senator to an executive or judicial office. Replacing Scalia with another conservative would not even change the Supreme Court status quo, which upholds affirmative action, gay marriage, abortion rights, and Obamacare by 5-4 majorities.

Third: Under power delegated by Congress, Trump should commit to reimposing sanctions against Iran for its aggression in the Middle East and its missile development program. He should not tear up the nuclear deal immediately. That would only release Iran from its commitments to reduce its stockpile of nuclear materials, after the United States had already upheld its side of the deal by transferring billions of dollars in frozen funds.

The Iran deal doesn't have much of a future. Iran may renounce the nuclear deal when Trump reimposes sanctions. But it is better for Iran to pull out first. In the meantime, President-elect Trump can show Tehran - and Congress - that he is not closing his eyes to Iranian aggression. If Iran violates the deal, President Trump can terminate it unilaterally. This move would appeal to moderates, as a majority of the House and Senate voted to reject Obama's Iran deal in the first place.

To be sure, we have only one president at a time. Presidents-elect have historically said very little of substance before inauguration, even in extreme circumstances. In 1861, President-elect Abraham Lincoln said nothing in public about how he would respond to secession. In 1933, President-elect Franklin Roosevelt promised little about his response to the Great Depression.

But President-elect Trump approaches his inauguration with little public record or certainty over his true policy views. He could reassure his party and the American people by using presidential power to launch a few basic policy initiatives now.

Jeremy Rabkin is a professor of law at George Mason University School of Law.

John Yoo is a law professor at the University of California at Berkeley, a former Justice Department official, and coeditor of "Liberty's Nemesis: The Unchecked Expansion of the State."