Interfering in an ongoing federal investigation with the purpose of subverting the inquiry represents a classic case of obstruction of justice.

When the president of the United States engages in such meddling, his wrongdoing affronts the separation of powers and the system of checks and balances that was developed by the founders of the American experiment in order guard against any American repetition of what they had so recently revolted against: “the exercise of the Kingly Office” in a manner that could “pervert the same into a detestable and insupportable Tyranny.”

The essential response to such abuse is impeachment. It is the answer to the questions that George Mason posed in this regard to the Constitutional Convention on July 20, 1787: “No point is of more importance than that the right of impeachment should be continued. Shall any man be above Justice? Above all shall that man be above it, who can commit the most extensive injustice?”

This all matters today because Donald Trump has just meddled in an ongoing investigation—seeking to force the declassification of documents and text messages that are relevant to the inquiry into Russian influence on his campaign and his presidency. The president has ordered the Justice Department and Office of the Director of National Intelligence to begin the “immediate declassification” of key sections of the Foreign Intelligence Surveillance Act application for Carter Page, who once served as a foreign-policy aide to Trump. The president has also ordered the declassification of “all FBI reports of interviews prepared in connection with all Carter Page FISA applications” and “directed the Department of Justice (including the FBI) to publicly release all text messages relating to the Russia investigation, without redaction, of [former FBI director] James Comey, [former acting director of the FBI] Andrew McCabe, [former chief of the FBI’s Counterespionage Section] Peter Strzok, [former FBI lawyer] Lisa Page, and [former associate deputy Attorney general and former director of the Organized Crime Drug Enforcement Task Force] Bruce Ohr.”

The White House is busy peddling the fantasy that the president is acting in the interest of “transparency.” But, as the Columbia Journalism Review has wisely noted, transparency talk is hypocritical coming from “our 45th president—who calls journalists ‘scum,’ refuses to release his tax returns or fully disclose his business ties, and calls for media ‘blackouts’ at executive agencies…”

The truth is that Trump is not promoting transparency. This is, as The Washington Post editorial board explains, an “obvious abuse of presidential power in a matter implicating himself.”

Former acting director of central intelligence John McLaughlin describes Trump’s unprecedented interference as “wrong on so many levels for Justice, law-enforcement, intelligence,” and argues that “This probably qualifies as the President’s most serious assault on the Justice system yet.”

McLaughlin is right that Trump’s intervention is problematic for law enforcement and national security. As Virginia Senator Mark Warner, the ranking Democrat on the Senate Intelligence Committee, explains it: “The President shouldn’t be declassifying documents in order to undermine an investigation into his campaign or pursue vendettas against political enemies. He especially shouldn’t be releasing documents with the potential to reveal intelligence sources.” Even though the information that is released may ultimately harm Trump, Harvard law professor Laurence Tribe wisely notes that “Declassifying FISA documents while the investigation of which they’re a part is ongoing is an especially grave species of obstruction of justice—an obstruction that endangers intelligence methods and sources, risks lives, and hurts national security.”

Along with the practical issues, Trump’s wrongdoing raises profound constitutional concerns.

“President Trump, in a clear abuse of power, has decided to intervene in a pending law enforcement investigation by ordering the selective release of materials he believes are helpful to his defense team and thinks will advance a false narrative,” says California Congressman Adam Schiff, the ranking Democrat on the House Intelligence Committee. “With respect to some of these materials, I have been previously informed by the FBI and Justice Department that they would consider their release a red line that must not be crossed as they may compromise sources and methods,” Schiff added. “This is evidently of no consequence to a President who cares about nothing about the country and everything about his narrow self-interest.”

California Congressman Eric Swalwell, a member of the Intelligence and Judiciary committees, was appropriately blunt. Calling the president “lawless…absolutely lawless,” Swalwell pointed out that “[Trump] is the subject of an investigation. Using his power to selectively release classified information is an abuse of power. His days of unchecked abuse are numbered. Tick tock. We will just mark this as another exhibit.”

That exhibit should support an article of impeachment like the first article that targeted President Nixon in 1974. Approved by the House Judiciary Committee on bipartisan 27-11 vote, the article declared that “In his conduct of the office of President of the United States, Richard M. Nixon, in violation of his constitutional oath faithfully to execute the office of President of the United States and, to the best of his ability, preserve, protect, and defend the Constitution of the United States, and in violation of his constitutional duty to take care that the laws be faithfully executed, has prevented, obstructed, and impeded the administration of justice.”

In particular, the committee argued that Nixon must be impeached “for interfering or endeavoring to interfere with the conduct of investigations by the Department of Justice of the United States, the Federal Bureau of Investigation, the office of Watergate Special Prosecution Force, and Congressional Committees.”

This is the type of interference in which Trump is now engaging.

In Nixon’s time, Republicans joined Democrats in moving to hold a Republican president to account for obstruction of justice. These are different times. But there can be no excuses for members of Congress, no matter what their partisanship, who fail to recognize that the impeachment power exists to address precisely so lawless a presidency as that of Donald Trump.

(John Nichols wrote the foreword to the book The Constitution Demands It: The Case for the Impeachment of Donald Trump (Melville House), to which John Bonifaz contributed, along with constitutional lawyers Ron Fein and Ben Clements.)