The subpoena of former Vice President Mike Pence by the Department of Justice could set up a showdown over executive privilege.

Former President Donald Trump has repeatedly invoked the legal protection to block testimony of his allies and subpoenas related to the Jan. 6, 2021, attack on the U.S. Capitol. He may do so again in response to Pence’s subpoena.

Pence’s role in presiding over the electoral certification process made him a central figure in the Jan. 6 proceedings. In the days and hours before the mob attacked the Capitol, Trump subjected his vice president to intense pressure to overturn the 2020 election results. Pence was also present during several critical meetings with Trump and his allies ahead of Jan. 6.

There are not many details known about the subpoena issued to Pence by Jack Smith, the special counsel appointed late last year by Attorney General Merrick Garland. Smith is investigating Trump’s role in the Jan. 6 attack, as well as a probe into the former president’s handling of classified documents.

What is executive privilege?
Executive privilege is a legal protection for the president of the United States that allows them to shield some of their private communications from Congress and courts.

«At its core, it’s the idea that some documents and some information — if it were disclosed — would damage, harm the public interest or harm the country in some way,» explained Jonathan Shaub, a former Justice Department official who is now a professor at the University of Kentucky College of Law.

In theory, the protection allows a president’s advisers to give candid advice free from fear of public disclosure, making the president’s deliberations more productive, legal experts explained.

Executive privilege isn’t explicitly stated in the Constitution. Instead, it implicitly stems from Article II, outlining the power of the executive branch, and the separation of powers.

The idea dates to the Nixon administration, when a special prosecutor leading the investigation of the Watergate break-in subpoenaed President Richard Nixon for tapes and transcripts of conversations related to the burglary.

Nixon refused, and the case went to the Supreme Court. Ultimately, Nixon lost and was forced to hand over the tapes (after which he resigned).

What are the limits of executive privilege?
Although the court ruled against Nixon, it ultimately found that there is confidentiality interest in communications between a president and their senior-most advisers. But, the court specified, there’s one very clear limit — executive privilege does not apply when the communications are relevant to a criminal investigation.

For example, in Nixon’s case, the Supreme Court found a compelling interest in the criminal case against the Watergate burglars, since there was a «demonstrated, specific need for evidence in a pending criminal trial.»

Otherwise, the limits of the doctrine are very much a live debate, legal experts said.

«Executive privilege, when it exists, is not absolute. It’s always weighed by courts against the interests served by disclosing the information to the authorities who are seeking it,» Jessica Roth, a professor of law at Yeshiva University, told NPR last year.

It’s also not clear the extent to which a former president can claim it. After Nixon left office, Congress tried to compel him to turn over his presidential records, which he refused to do, citing executive privilege. That case also went to the Supreme Court, which again ruled against him — but left some ambiguity over whether former presidents could assert the privilege in the future.

Practically speaking, most disputes over executive privilege have been resolved through compromise between those asking for the documents or testimony, and those providing, legal experts said.

How has it come up in regards to Jan. 6?
Trump has argued many times before that his communications related to Jan. 6 are privileged. Those claims have not always been successful.

The issue arose repeatedly during the House committee’s investigation of the Jan. 6 attack on the Capitol. The committee subpoenaed numerous Trump aides and advisers, several of whom refused to testify on the basis of executive privilege. (The DOJ brought criminal charges for two of those advisers: One, Steve Bannon, was found guilty of contempt of Congress after his refusal to testify. The contempt case against another, Peter Navarro, is expected sometime this year.

Trump also tried to sue the heads of the House select committee and the National Archives to block the release of Jan. 6-related documents, but a court ruled against him last year.

The former president has also tried to use executive privilege to block testimony to a federal grand jury, but those efforts have been less successful, the New York Times has reported.

A subpoena issued by the Department of Justice is harder to ignore, said Victoria Nourse, a former DOJ official who also served as chief counsel to the vice president of the United States under then-Vice President Joe Biden. Congressional subpoenas can lack teeth because the process to get a judge to enforce them can be slow, she explained.