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Questions have arisen over the constitutionality of former President Donald Trump’s impending trial in the Senate. Trump is the first president to be impeached twice and would be the first ex-president to have his impeachment tried in the Senate while out of office.

House Democrats are expected to send the articles of impeachment to the Senate soon but the timing remains unclear. Sources have told CNN it could be as early as Friday.

Following Trump’s most recent impeachment in the House, former US Circuit Court Judge J. Michael Luttig weighed in on some constitutional questions, writing on January 12 in the Washington Post that “Congress loses its constitutional authority to continue impeachment proceedings against” Trump after he leaves office because “the Senate’s only power under the Constitution is to convict — or not — an incumbent President.”

Since then, several Republican senators, including Tom Cotton, Joni Ernst and Roger Marshall, have said they don’t think it would be constitutional to convict Trump in the Senate after he’s left office.

Senate Democrat Richard Blumenthal called arguments questioning the constitutionality “bogus” saying that “[T]here’s nothing in the Constitution that prevents any federal officer from being tried after they’re out of office.”

Facts First: Given the limited language in the Constitution on impeachment, legal experts disagree about whether the Senate can convict a former president. However, with Democrats holding slim control of the Senate, there’s no reason to think the trial won’t go forward.

Under the Constitution, the House can impeach a President for “treason, bribery or other high crimes and misdemeanors.” Then the Senate holds a trial and needs a two-thirds majority to convict and remove the President from office. Another vote would be necessary to bar the then ex-President from holding office again, but this vote would require only a simple majority.

The Constitution doesn’t specifically address convicting an ex-President but simply says “The President,” VP and all civil officers “shall be removed from Office on Impeachment for, and Conviction of, Treason, Bribery, or other high Crimes and Misdemeanors.”

Legal experts and precedents

A January 15 Congressional Research Service report notes that while the Constitution “does not directly address” the issue, most scholars have concluded that Congress does have the authority to impeach and convict a former President.

In op-eds for the Washington Post and the New York Times, respectively, Harvard Law School professor Laurence Tribe and CNN legal expert Steve Vladeck, argue that such a trial is constitutional in part because the Senate’s role in an impeachment is defined by two separate judgments: one to remove and then subsequently another to disqualify.

Tribe noted that even though a former officer such as the President can no longer be removed from office, that “has no bearing on whether such an ex-officer may be barred permanently from office upon being convicted.”

And according to Vladeck, the Senate’s power to disqualify an individual from future office is “the primary evidence” that trying the impeachment of a former officer is constitutional.

“Were it otherwise, an officer facing impeachment, or an officer who has already been impeached and is about to be removed, could also avoid disqualification simply by resigning,” Vladeck wrote.

Yale University law professor Akhil Reed Amar agreed, telling CNN’s Joan Biskupic that “It would be absurd if you could escape by resigning one step ahead of the gavel.”

Biskupic also reported that Tulane Law School professor Ross Garber, who asserts that the Senate may try only a sitting president, nonetheless said the 1993 precedent, in which Mississippi federal judge Walter Nixon unsuccessfully challenged Senate trial procedures in his impeachment case, would likely make it difficult for Trump to find a court that would hear his appeal.

“I think the reasoning of Nixon (case) could be a problem for any Trump litigation effort,” Garber told CNN, adding that “it is very unlikely the Supreme Court would stop the Senate in its tracks in a direct Trump challenge to its jurisdiction.”

In addition to the Nixon case, a Congressional Research Service report from November 2019 cites – as precedent – the 1876 impeachment trial of Secretary of War William W. Belknap, who was tried and acquitted even after he’d resigned his office. The Senate ultimately upheld its authority to try Belknap even after his abrupt resignation – though some senators who voted to acquit indicated they did so because they felt the Senate lacked jurisdiction over Belknap once he was no longer in office.

CNN’s Joan Biskupic contributed to this article.