When I defended former President Trump against a Democratic effort to impeach and remove him on grounds that I believe are unconstitutional, I predicted that when the Republicans gained control of the House, they would use that precedent as a justification for trying to impeach the next Democratic president.

Sure enough, Rep. Lauren Boebert (R-Colo.) has introduced articles of impeachment that replicated what the Democrats had done just three and a half years earlier.

In December 2019, Democrats charged Trump with “abuse of power” and “obstruction of Congress.” I argued, successfully, that these articles did not satisfy the constitutional criteria for impeachment: treason, bribery or other high crimes and misdemeanors.

Nearly all the Republicans in both Houses of Congress agreed with my argument that criminal-type behavior akin to treason or bribery is required, and they voted against the articles of impeachment passed by the Democratic House.

Now some of these same Republicans are supporting Biden’s impeachment on grounds similar to the ones they rejected when they were directed against the Republican president: “Abuse of power” (Article I), and “dereliction of duty.” (Article II).

These alleged grounds do not appear in the Constitution, and the second one was implicitly rejected by the Constitutional Convention when proposals to include “malpractice for neglect of duty,” “neglect in the execution of his office” and “maladministration” were withdrawn at the insistence of James Madison, the father of our Constitution.

Once again partisanship trumps principle, and consistently is regarded as a weakness in the game of political hardball.

The irony is that there might actually be constitutionally valid grounds for impeaching President Biden under two possible circumstances: 1) if it turns out that Biden’s son, Hunter, was actually sitting next to his father and was aware that he invoked the former vice president’s name when he communicated a threat to a Chinese businessman; and 2) if a high crime committed by a former vice president and future president during his interregnum as a private citizen can satisfy the criteria for impeachment. The first is a question of fact; the second is a matter of constitutional interpretation.

I personally doubt that Joe Biden was aware that his son was invoking his name and power when and if he sent that possibly extortionate message. But if that message is real, it certainly requires that Hunter Biden be placed under oath to admit or deny he sent the message; admit or deny that he was telling the truth when he said his father was sitting next to him; admit or deny that his father was aware he was sending the message; and admit or deny that his father was aware of the content of the message.

The allegation that a former vice president and current president may have been complicit in an arguable extortion plot is a serious one that requires further investigation. In the unlikely event that it were confirmed, it would raise a profound, difficult and unresolved question of constitutional interpretation: namely whether a president can be impeached and removed for a high crime committed before he assumed the presidency.

Extortion or attempted extortion is a high crime akin to bribery and thus — if proved — would be a constitutional ground for impeachment if it had been committed by a sitting president during his presidency. But what if it had been committed earlier?

Vice President Spiro Agnew was accused of engaging in extortion and bribery. Although the accusation was made during his vice presidency, the alleged bribery occurred while he was still governor of Maryland (though he allegedly received some of the payments while vice president).

He pleaded no contest to a tax felony as part of a plea bargain that included his resigning the vice presidency. Accordingly, we do not know whether he could have or would have been impeached for conviction while vice president of a serious felony he committed before assuming that office.

It is unlikely that this question will be presented in the Biden case, because credible evidence may not exist proving that Biden committed any impeachable offenses between the time he served as vice president and president — or at any other time. But we won’t know that unless the current allegations, which include claims of incriminating recordings, are thoroughly investigated.

If Republican House members are determined to impeach Biden, they should focus their investigative resources on specific allegations of serious crimes which, if true, may rise to the level of possibly impeachable offense. It will not do to rely on vague, partisan accusations of misconduct which, even if true, would not satisfy the criteria for impeaching and removing a duly elected president, as they themselves recently argued.

Alan Dershowitz, professor emeritus for Harvard Law School, is the author of numerous books, including his latest, “The Price of Principle” and “Get Trump.” He is also the host of The Dershow on Rumble. Follow him on Twitter @AlanDersh.