WASHINGTON — Attorney General Merrick B. Garland has long said that the Justice Department is up to the task of investigating former President Donald J. Trump, whose final weeks in office included his supporters attacking the Capitol as he refused to acknowledge his election loss.
That assertion was part of Mr. Garland’s desire to show that the department could operate above partisanship, acting as neither the weapon nor the enemy of any president or party. The real and perceived political land mines that accompany an investigation into Mr. Trump could be navigated, Mr. Garland suggested, by strictly following the rule of law.
“The rule of law means that the law treats each of us alike,” Mr. Garland has stated. “There is not one rule for friends, another for foes; one rule for the powerful, another for the powerless.”
But Mr. Garland’s hopes are being tested by Mr. Trump’s apparent plan to announce that he will run again for the White House, a step that would transform him from a former president into an electoral opponent of President Biden at a time of extreme political polarization — an environment leading the Justice Department to weigh whether to appoint a special counsel to handle open criminal inquiries related to Mr. Trump.
A special counsel, who is typically appointed by the attorney general, would have more autonomy to run an investigation than other federal prosecutors usually would. That person has more independence than a United States attorney, but any final decisions on whether to charge Mr. Trump would still rest with Mr. Garland and the department’s top leaders.
The former president faces a series of investigations, including his handling of sensitive national security documents and his efforts to retain power after his election loss, and it remains an open question whether the department will ultimately bring charges against him.
A special counsel could theoretically shield the department from the perception that an investigation into Mr. Trump is a partisan attack on Mr. Biden’s top political opponent. But it could also imply that the Justice Department on its own could not be trusted by all Americans to make decisions about holding Mr. Trump to account.
Whether Mr. Garland names a special counsel to investigate Mr. Trump, the fact that the Justice Department is considering such a move for the second time in five years in part reflects the extent to which the former president has undercut faith in the institution’s ability to fairly investigate him.
“Our justice system is faced with one of its greatest challenges of its more than 250-year history,” said Claire Finkelstein, a law professor at the University of Pennsylvania and the founder of the Center for Ethics and the Rule of Law.
“There is no reason, under federal law, that a former president or a presidential candidate can’t be indicted,” Ms. Finkelstein said. “But the nature of our politics has become so polarized that there is no criminal investigation, no indictment, no legal action that won’t be perceived as just another part of the poisonous partisan politics in the U.S. today.”
By law, special counsels are appointed when an investigation presents a conflict of interest for the department and when it serves the public interest for someone with relative independence from the department to assume responsibility for the matter.
Should Mr. Trump declare his candidacy, legal experts say that investigating a sitting president’s top political opponent in a coming election could present more of a conflict for Biden’s Justice Department than it has so far faced in its investigations.
“Once Trump is more than a former president, but a declared candidate for the presidency, it’s smart for the department to evaluate whether a special counsel is appropriate,” said Andrew D. Goldstein, a prosecutor who worked on the obstruction investigation into Mr. Trump conducted by the special counsel Robert S. Mueller III.
It would not be the first time that a special counsel has had to handle a matter related to Mr. Trump.
After Mr. Trump fired the F.B.I. director James B. Comey in May 2017, the department tapped Mr. Mueller to complete the bureau’s Russia investigation and determine whether Mr. Trump obstructed that inquiry. The Mueller report found no evidence that the Trump campaign had broken the law in its dealings with Russia, but left prosecutors to decide the obstruction question after Mr. Trump left office. The attorney general at the time, William P. Barr, interpreted the report to clear him of wrongdoing.
After Republicans, led by Mr. Trump, continued to denounce Mr. Mueller’s work, John H. Durham was appointed to examine whether the Russia investigation had been a partisan assault. (Mr. Durham is expected to provide his findings to Mr. Garland in the coming months. He has not charged any high-level government officials.)
Now the department could appoint someone with broad oversight over the current investigation into Mr. Trump’s handling of sensitive government documents after he left office, which includes questions about whether Mr. Trump or his aides intentionally misled investigators and tried to obstruct the inquiry.
Justice Department officials had hoped that they could weigh the evidence themselves and make a convincing case based on the facts and the law. By hewing to the rules, they hoped to show that the justice system worked, even in the face of Mr. Trump’s multipronged attacks.
But it is not clear that appointing a special counsel will shore up the public’s faith in the department.
It is debatable whether special counsels, and independent counsels before them, have ever succeeded in their implicit mission to help the country reach consensus on highly contentious matters. Beyond Mr. Mueller and Mr. Durham, those include Leon Jaworski, who pursued the investigation into President Nixon during Watergate, and Ken Starr, who led the investigation into President Clinton.
Once Mr. Trump is involved, it is difficult to imagine a world where a special counsel could successfully act as a neutral arbiter with fewer real or perceived conflicts than the attorney general.
As director of the F.B.I., Mr. Mueller was credited with shaping the United States’ response to the post-9/11 terrorist threat. But Mr. Trump undermined that reputation with false statements and wild accusations, painting Mr. Mueller, a Republican who had worked in the Reagan and both Bush administrations, as a Democratic partisan hack engaged in a witch hunt.
“Institution after institution that has depended for its legitimacy on its impartiality is finding that it’s no longer possible to speak with the authoritative voice of neutrality,” Ms. Finkelstein said.
Finding a special counsel would be a challenge in an era of rampant partisanship. The candidate would need to be respected by Republicans and Democrats alike, and be willing to withstand censure by Mr. Trump.
And the rules governing the special counsel make clear that Mr. Garland would ultimately decide whether to make any of the investigation’s findings public and whether to prosecute Mr. Trump.
If past investigations involving Mr. Trump are any guide, a significant portion of the country will believe Mr. Garland erred, no matter what the evidence suggests. A special counsel will not change that.