Donald Trump’s commutation of Roger Stone’s jail sentence is an act of blatant corruption. The federal judge who presided over his trial stated that Stone was prosecuted for “covering up for Trump.” Trump’s commutation is a reward to Stone, his close political adviser, for that cover-up. By using the pardon power to shield himself from accountability, Trump perverted and abused that power. The commutation may also be a crime.

During his 2019 confirmation hearings, Attorney General Bill Barr said as much. “Do you believe a president could lawfully issue a pardon in exchange for the recipient’s promise to not incriminate him?” Senator Pat Leahy asked him. “No,” Barr replied. “That would be a crime.” We now know Barr and others advised Trump against commuting Stone’s sentence. This week, Stone denied any such quid pro quo, but that’s simply not credible.

Pardoning a confederate to protect oneself was foreseen by the framers of our Constitution—and they spelled out the consequences: impeachment. Apparently, they thought that such a drastic remedy would protect the country by deterring any president contemplating such a course of action—or, if it didn’t act as a deterrent, to prompt the removal of the president. But the Republican-controlled Senate has clearly shown its unwillingness to remove Trump from office, regardless of the gravity of his misconduct.

Stone has lots of damaging information about Donald Trump and his campaign’s outreach to Russia for help in the 2016 presidential election. Stone essentially admitted that recently, when he told a journalist, “He knows I was under enormous pressure to turn on him. It would have eased my situation considerably. But I didn’t.” He must have figured that his life would be even easier if he covered up for Donald Trump. Pots of gold would lie at the end of that rainbow.

As we now know from the recently released portions of the Mueller report, Stone could have driven a knife through the heart of the Trump presidency. Witnesses said that Trump spoke with Stone on several occasions about Wikileaks’ release of e-mails that were harmful to presidential candidate Hillary Clinton. (The e-mails had come from Russian hacking.) The witnesses described a Trump who welcomed the information he received from Stone and did not object to receiving and benefiting from Russian hacks and Wikileaks’ releases. Stone could fill in the details of those conversations.

Stone also communicated directly with the GRU, Russia’s military intelligence agency responsible for interfering in the 2016 election, and could describe those communications and Trump’s response if and when he shared them with him. If Stone had turned and provided truthful information, it could have led to Trump’s impeachment, defeat at the polls this November, and/or prosecution, when he leaves office.

In Watergate, along with hush-money payments, President Richard Nixon secretly authorized offers of pardons to the burglars to keep them quiet. Although the pardons were never granted, authorizing them was one of the grounds for the House Judiciary Committee’s bipartisan impeachment vote against Nixon—and it was part of Nixon’s obstruction of justice.

Nixon short-circuited the impeachment effort by resigning, and President Ford stopped any possibility of prosecuting Nixon by pardoning him. Pardoning Nixon—an unpardonable act, in my view—caused Ford’s defeat in the next presidential election. In the end, the American people demanded accountability for Nixon’s presidential crimes and abuses of power. Nixon paid a price for Watergate by resigning in disgrace, and Ford lost his election for protecting Nixon.

The same thing may and should happen to Donald Trump. Americans need to understand the outrage Trump has committed against our democracy. To every appearance, Trump has undermined our 2016 elections by soliciting and receiving Russian interference on his behalf, dangling the possibility of a pardon to encourage Stone to lie and cover up before a congressional committee investigating collusion with Russia, and then commuting Stone’s sentence so that he would never have to go to prison for covering up. Trump seems to have been concerned that Stone might decide to turn, even at the last minute, to avoid jail—something Trump could not risk.

Unfortunately, the Department of Justice’s Office of Legal Counsel, which bends to protecting presidents, has opined that a president cannot be prosecuted while in office. But the Constitution makes it clear that a president can be prosecuted after leaving office.

A new attorney general, committed to protecting the integrity of our elections, can and should investigate the pardon, either directly or through a special counsel.

A new Congress should review the Constitution’s pardon power and propose amendments that would prevent its use by a president to protect any campaign adviser or aide, presidential appointee, or family member. A self-pardon should also be clearly banned, as should a pardon by any succeeding president of the prior president.

And finally, the American people need to reject Donald Trump’s cynical and criminal presidency by voting him out of office in November. We need to start undoing the horrific damage he has done to our country and our democracy—and we can’t start soon enough.