Now that the House has impeached President Donald Trump for a second time, one question that is confounding many people is whether the Senate may proceed with an impeachment trial after Trump leaves office. The question is not new, and neither is the answer: The Senate may proceed with Trump’s impeachment trial, regardless of whether he is still in or out of office.

Besides the arguments I have previously made that the Constitution mentions no time barriers on impeachment anywhere in the six clauses defining the process and the dangers of allowing presidents to escape responsibility for misconduct done in or discovered after their last few days in office, there are three other compelling arguments that post-presidential impeachment is legitimate.

The first is that a president who returns to private life is not like other private citizens. He is different because he becomes an ex-president, and as an ex-president he has an office and certain privileges such as briefings, and entitlements such as Secret Service protection. An ex-president occupies, in other words, a special kind of office, and therefore once someone leaves the presidency, he is still subject to conviction by the Senate (by at least 2/3 of the Senate as required in the Constitution) and removal from the office he holds as ex-president. His removal, via a two-thirds vote in the Senate, would likely strip him of whatever powers and benefits he has as an ex-president and through a separate vote after he is convicted, Trump may be subject to the unique constitutional penalty of disqualification, which the Constitution expressly recognizes as one of the two sanctions that may be imposed on an official convicted in an impeachment trial.

Post-presidential impeachment is also legitimate because the Senate rules, initially drafted by Thomas Jefferson when he was vice-president, allow it. They provide that once the Senate has received the articles of impeachment, the Senate must “immediately” proceed with a trial.

Once the Senate receives the articles of impeachment against Trump, the Senate has no choice but to begin an impeachment trial. Every senator knows that the Senate has a long tradition of following its rules, and this is why Senator Mitch McConnell (R-Kentucky) will not reconvene the Senate until the day before Joe Biden’s inauguration as the 46th president of the United States: He knows the Senate would have to begin a trial, and therefore he may be taking advantage of the Senate’s being in recess now so that Chuck Schumer, a Democrat who will become majority leader on Jan. 20, will take the heat for starting Trump’s second impeachment trial after Trump has left office. No one is more skilled at the use of congressional procedures than McConnell, but even he surely knows the Senate must begin an impeachment trial, even after the president leaves office.

The third reason that post-presidential impeachment is legitimate is perhaps the most compelling: On three separate occasions after an official left office, Congress proceeded with an impeachment and a trial of the impeached official. These three precedents provide a strong foundation for the Senate’s conducting a second impeachment trial of Trump. Some commentators overlook or dismiss these precedents because they did not involve presidents, but that makes no sense, since there is only one impeachment clause, which subjects presidents and every other impeachable official to the same process: They “shall be removed from office on impeachment for and conviction of treason, bribery, or other high crimes and misdemeanors.”

Those contesting the legitimacy of post-presidential impeachment trials read this language as suggesting impeachment applies only when impeachable officials are in office because it speaks of “removal” immediately following up a “conviction” and thus it only makes sense if the person is in an office from which he may be removed. Yet, as we will see, that is not consistent with the uniform practice of impeachments in our history.

The first impeachment held after the official left office was the very first impeachment in American history. In 1797, President John Adams sent evidence to Congress indicating that North Carolina Senator William Blount had plotted to help the British seize parts of the United States. After studying the evidence, the House began an impeachment of Blount, but the Senate expelled him before the impeachment proceedings were done. (He was not present for any of these proceedings.) Yet, as Professor Laurence Tribe of Harvard Law School recently noted, one of the House Managers (appointed to prosecute the case in the Senate for a conviction) and Blount’s lawyer agreed that a civil officer was subject to impeachment after leaving office. In early 1798, the House proceeded to investigate the matter further and impeached Blount. Despite the fact that Blount was no longer in office, the Senate began his impeachment trial (with Jefferson presiding). In the trial, the Senate, in a narrow vote, agreed with Blount’s lawyer’s objection that a senator was not “a civil officer” and therefore not amenable to impeachment. The key lesson from this episode is that it was done by the First Congress after Blount left office, and the usual rule in constitutional law is that we defer to the First Congress because most of its members helped to draft or ratify the Constitution. The First Congress also bifurcated voting in the impeachment trial, requiring senators first to vote on whether to convict and then, secondly, voting on the sanction to be imposed. When the Senate does hold a second trial of Trump, it will be following what the First Congress once did.

The second precedent is even more analogous to Trump’s situation. In 1861, West Humphreys left his federal judgeship to join the confederacy as a judge. A year later, the House impeached him, and the Senate convicted, removed, and disqualified him from holding any federal office again. If one merely looks at presidential impeachments as a guide in answering the question whether Trump may be tried after leaving office, this precedent will be among those overlooked. No serious impeachment scholar has ever contested Humphreys’ impeachment or conviction though he had abandoned his office a year before his impeachment, conviction, removal, and disqualification.

The third precedent involves President Ulysses Grant’s secretary of war, William Belknap. Belknap was corrupt, and in 1876 the House had begun to consider his impeachment for bribery. Belknap was desperate to stop the impeachment, so he rushed over to the White House and pleaded with the president to accept his letter of resignation before the House formally impeached him. He hoped his resignation would block the House, but it did not: The House proceeded to impeach him. In the impeachment trial, the Senate voted 37-29 that Belknap was “amendable to trial by impeachment [notwithstanding] his resignation of said office.”  The Senate voted to convict Belknap by a similar vote, which fell short of the two-thirds required for a conviction.

True, the Congress did not proceed with an impeachment or trial for Richard Nixon once he resigned from office. But that was not because of a constitutional limitation. It was because congressional leaders believed they could still impeach Nixon but declined because they agreed with President Gerald Ford that, after two years of investigating Nixon, it was time to put the entire Nixon matter behind us. As Ford memorably declared at the time, “our long national nightmare is over.”

What is the lesson of these precedents? That the Senate will hold a trial of any impeached officials, regardless of whether they are still in office, and it is during this phase that impeached officials may raise affirmative defenses, such as arguing that the Senate lacks the power to impeach them because they are no longer in office. The Senate is charged with deciding whether it may convict someone and impose (through separate votes) the sanctions available in impeachment trials, and its decision is final. The Senate has skipped a conviction vote only once and that was because the official (Blount) had been a senator, who is subject to expulsion but not impeachment, and not because he was no longer in office.

Fast forward to this past week. The House impeached Trump for incitement to insurrection, but the article of impeachment has not yet been delivered to the Senate. Once the Senate receives the article, the Senate will do what it has always done – immediately begin an impeachment trial. In this case, Trump cannot escape the trial, or the consequences of his misconduct, because he has left the presidency. He can defend himself as all impeached officials have done in their impeachment trials (Blount’s lawyer was there), but the Senate will conduct an impeachment trial, a legitimate one, because that it is what it has always done – with no exception.

Image: Barbed wire is installed on security fencing surrounding the U.S. Capitol on January 14, 2021 in Washington, DC. Security has been increased throughout Washington following the breach of the U.S. Capitol last Wednesday, and leading up to the Presidential Inauguration. Photo by Stefani Reynolds/Getty Images