In naming a special counsel to investigate the presence of classified documents at President Joe Biden's Delaware home and former office, Attorney General Merrick Garland described the appointment as underscoring the Justice Department's commitment to independence and accountability in particularly sensitive investigations.

If those words sounded familiar, they should.

Garland used identical phrasing in November in appointing a different special counsel for a different politically explosive investigation into different classified documents for a different political figure — this one, into the retention of top-secret records at former President Donald Trump's Florida estate, Mar-a-Lago.

The Justice Department has, of course, investigated White House matters in the past. But it's now confronting a unique phenomenon: simultaneous special counsel investigations — albeit with dramatically distinct fact sets — involving two presidents, jostling for time, attention and perhaps funding as well. Another special counsel appointed during the Trump administration to investigate the origins of the FBI's Trump-Russia investigation also remains at work.

The special counsel confluence underscores how a Justice Department that for nearly two centuries has had a mandate of prosecuting without fear or favor has found itself entangled in extraordinary ways in presidential politics. Even as Garland made a point Thursday of saying the department's own "normal processes" can handle all investigations with integrity, the appointment seemed to nod to a reality that probes that involve a president — in this case, Garland's boss — are different.

It places Garland under pressure to reassure the public that both investigations, though factually different, are handled in similar manners.

"I think it's not only the right decision and a prudent decision. I think it's a politically necessary decision," said Solomon Wisenberg, who served as deputy to Ken Starr during the 1990s independent counsel investigations into then-President Bill Clinton.

"Why," he added, "give yourself the grief of the comparison of the two situations" of a special counsel for Trump, a Republican, but not for Biden, a Democrat.

Brandon Van Grack, a former Justice Department prosecutor who served on then-special counsel Robert Mueller's team as it investigated ties between Russia and Trump's 2016 presidential campaign, said appointing a special counsel can help expedite an investigation, ensure it has appropriate resources and "creates at least the perception of impartiality and fairness."

"With respect to this decision, this specific decision, it's at least understandable why the attorney general would want all of those benefits," Van Grack said.

The appointment was announced hours after the White House disclosed that a document with classified markings from Biden's time as vice president was found in his personal library, along with other classified documents found in his garage. Garland said Biden's lawyers informed the Justice Department on Thursday morning of the discovery of a classified document at Biden's home. FBI agents first retrieved other documents from the garage in December, he said.

The White House earlier this week acknowledged that the president's personal lawyers found a "small number" of classified documents at the office of his former institute in Washington. That discovery led Garland to ask the U.S. attorney in Chicago, John Lausch, a Trump administration holdover, to investigate the matter, though Lausch is now preparing to leave the Justice Department.

On Thursday, Garland named Robert Hur, a former senior Justice Department official in the Trump administration who served as U.S. attorney in Maryland, to serve as special counsel. He joins Jack Smith, a former public corruption prosecutor who is investigating the documents found at Mar-a-Lago and efforts to undo the 2020 election, and John Durham, who's secured one guilty plea and lost two criminal trials in three and a half years investigating the Trump-Russia probe.

The position of Justice Department special counsel is a fairly new creation, enacted by Congress in 1999 following a bruising and politically divisive independent counsel investigation that resulted in Clinton's impeachment by the House but acquittal in the Senate. The purpose was to ensure ultimate Justice Department oversight of sensitive investigations rather than vest them with an independent prosecutor who could operate unchecked and without supervision.

Though the attorney general retains ultimate authority over a special counsel's decisions, special counsels do have the latitude to bring whatever cases they see fit. They are funded by the Justice Department, can bring on their own prosecutors, are entitled to office space and are often expensive — the Mueller probe, for instance, rang up more than $25 million in costs in its first year and a half.

How much detailed interaction Garland will have with his special counsels is unclear, though he said Thursday that Hur "will not be subject to the day-to-day supervision of any official" at the Justice Department. Officials have noted that they are expected to accept a special counsel's recommended course of action unless it's far outside the department's normal process.

It also remains unclear whether either classified documents investigation will result in criminal charges or how, if at all, the two special counsel probes might affect each other. Though the Biden probe is much less mature than the Trump one, there's been no hint of the same allegations already leveled publicly in the Mar-a-Lago matter. The Justice Department has also long held the belief that a sitting president cannot be indicted.

Mary McCord, a former Justice Department national security official, said she expected Smith to weigh the Mar-a-Lago facts and evidence just as before. The possibility that that case could end with an indictment existed well before the appointment of a special counsel, thanks to the public release of a search warrant affidavit that laid out possible crimes.

Even before a special counsel was appointed, she said, "the American public was already thinking this was a criminal investigation."

In that case, FBI officials have said that in addition to the unlawful retention of national defense information, they're also investigating potential obstruction of that probe. Trump representatives for months failed to give the classified documents back to the National Archives and Records Administration and, according to the Justice Department, did not fully comply with a subpoena that sought their return.

That suspicion led agents to return to Mar-a-Lago last August with a search warrant, collecting more than 100 documents with classification markings — including at the top-secret level — that were commingled among Trump's personal belongings.

But, Wisenberg said, an investigation is needed to establish how substantively different the fact patterns are.

"That's up to the people doing the investigation to determine," he said.