2016 Campaign Looms Large as Justice Dept. Pursues Jan. 6 Inquiry

As the Justice Department investigation into the attack on the Capitol grinds ever closer to former President Donald J. Trump, it has prompted persistent — and cautionary — reminders of the backlash caused by inquiries into Mr. Trump and Hillary Clinton during the 2016 presidential campaign.

Attorney General Merrick B. Garland is intent on avoiding even the slightest errors, which could taint the current investigation, provide Mr. Trump’s defenders with reasons to claim the inquiry was driven by animus, or undo his effort to rehabilitate the department’s reputation after the political warfare of the Trump years.

Mr. Garland never seriously considered focusing on Mr. Trump from the outset, as investigators had done earlier with Mr. Trump and with Mrs. Clinton during her email investigation, people close to him say.

As a result, his investigators have taken a more methodical approach, carefully climbing up the chain of personnel behind the 2020 plan to name fake slates of Trump electors in battleground states that had been won by Joseph R. Biden Jr.

As prosecutors delve deeper into Mr. Trump’s orbit, the former president and his allies in Congress will almost certainly accuse the Justice Department and F.B.I. of a politically motivated witch hunt.

The template for those attacks, as Mr. Garland and the F.B.I. director, Christopher Wray, well know, was “Crossfire Hurricane,” the investigation into the Trump campaign’s connections to Russia, which Mr. Trump continues to dismiss as a partisan hoax.

The mistakes and decisions from that period, in part, led to increased layers of oversight, including a major policy change at the Justice Department. If a decision were made to open a criminal investigation into Mr. Trump after he announced his intention to run in the 2024 election, as he suggests he might do, the department’s leaders would have to sign off on any inquiry under an internal rule established by Attorney General William P. Barr and endorsed by Mr. Garland.

“Attorney General Garland and those investigating the high-level efforts to overturn the results of the 2020 election are acutely aware of how any misstep, whether by the F.B.I. or prosecutors, will be amplified and used for political purposes,” said Mary B. McCord, a top Justice Department official during the Obama administration. “I expect there are added layers of review and scrutiny of every investigative step.”

Mr. Wray appears to be proceeding with the same level of caution, in hopes of armoring the bureau against future attacks by making sure his agents operate by the book and keeping Justice Department leadership informed.

That means following the F.B.I.’s stringent rules and “not just doing the right thing, but doing it in the right way,” Mr. Wray has often said. It also means Mr. Wray would not go it alone, as his predecessor, James B. Comey, famously did.

The typically aggressive bureau, which used every investigative tool in its arsenal during the Russia investigation, had not even opened a case targeting fake electors by early fall 2021, months after details of the wide-ranging scheme were known publicly, two former federal law enforcement officials said.

In 2015, amid the outcry over Mrs. Clinton’s use of a personal email account, senior F.B.I. officials — without consulting with top department officials, including Mr. Comey — opened a criminal investigation into whether she had mishandled classified information.

In May 2017, the F.B.I. opened an obstruction investigation into Mr. Trump on its own, catching the leadership of the Justice Department off guard and setting off a political firestorm. The decision also fueled the suspicions of Mr. Trump and his supporters that the so-called deep state wanted to undermine his presidency.

In the aftermath of Mr. Trump’s election victory, Mrs. Clinton and her supporters blamed Mr. Comey, contending that his unusual public statements about the status of the investigation into her emails had inadvertently shaped the outcome of the race. The new president would soon find fault with the director, too.

Mr. Trump’s willingness to attack the Justice Department was front of mind for officials in the department and the bureau as they scrambled to respond to the Jan. 6 attack, and other efforts to reverse Mr. Trump’s loss, current and former officials said.

The lawyers running the department at the time, including the acting attorney general, Jeffrey A. Rosen, and the acting deputy attorney general, Richard P. Donoghue, had managed to stop Mr. Trump from usurping their power so he could remain in office illegally. They had no illusions about his willingness to undermine any investigations.

They also knew that many of their decisions would someday be made public. That fortified their inclination not to make any bold moves before President Biden’s team took over, in the event that their actions were publicly scrutinized in oversight hearings — especially if Republicans regained control of Congress.

The afternoon that rioters stormed the Capitol, Mr. Garland was finishing a speech on the rule of law. He watched on television as Congress turned into a crime scene that he would soon need to investigate.

Everyone who witnessed the attack “understands, if they did not understand before, the rule of law is not just some lawyer’s turn of phrase,” Mr. Garland said at a ceremony the next day. “Failure to make clear by words and deed that our law is not the instrument of partisan purpose” would imperil the country, he added.

Mr. Garland had been mulling the Justice Department’s role in democracy since the 1970s, when he worked for Attorney General Benjamin R. Civiletti to help codify changes that addressed Watergate-era presidential abuses of power.

In late March, when Mr. Garland took over the department, he embraced the bottom-up tactics already being used by the Trump-appointed acting U.S. attorney in Washington: round up and apprehend the assailants, and then perhaps their communications and interviews would yield information that would lead them to more powerful targets.

That approach — summed up by the mantra of investigating “crimes, not people” — sometimes led to tensions between top officials and the federal prosecutors in Washington who run the investigation day to day.

From the start, Mr. Garland and his top deputy, Lisa O. Monaco — a former senior official at the F.B.I. and a detail-oriented former federal prosecutor — set the bar high. But they did not constrain prosecutors from pursuing avenues they saw as supported by evidence: Ms. Monaco urged prosecutors to devote additional resources to investigating the funding of rioters, and potential links to foreign governments, according to a former department official.

The department did not appear to immediately seize on public revelations made in the fall of 2021 that a top Trump lawyer, John Eastman, had been pushing the fake electors scheme.

Yet gradually, mostly hidden from public view, they began to pursue that lead, and others that eventually led them to more directly question Mr. Trump’s involvement.

At the time, Christopher R. Kavanaugh, who had gained extensive domestic terrorism experience as a prosecutor in Charlottesville, Va., after the deadly far-right rally there in 2017, was assigned to manage the sprawling Jan. 6 investigation. The inquiry touched on nearly every state in the country and included hundreds of suspects.

When Mr. Kavanaugh left the role after hundreds of arrests in early October to become the U.S. attorney in Charlottesville, he was replaced by Thomas P. Windom, an aggressive if little-known federal prosecutor from Maryland who had also handled high-profile domestic terrorism cases.

Mr. Windom expanded the electors investigation, according to people with knowledge of the situation. He also kept a close eye on a separate inquiry by the department’s inspector general into Jeffrey Clark, a former Justice Department official who had been central to Mr. Trump’s unsuccessful effort in late 2020 to strong-arm the nation’s top prosecutors into supporting his claims of election fraud.

Both of those investigations were already gathering steam as the House committee examining Jan. 6 accelerated its far more public inquiry — one meant to pressure Mr. Garland into moving more quickly to pursue Mr. Trump.

By April, prosecutors had retrieved emails from senior officials in the Trump White House.

In June, the inspector general obtained warrants for the electronic devices belonging to Mr. Clark, Mr. Eastman and Ken Klukowski, another former Justice Department official. A lawyer for Mr. Klukowski said his client was fully cooperating with the Justice Department and would continue to do so.

And on Wednesday, after news broke that two top aides to former Vice President Mike Pence had appeared before a grand jury, Mr. Windom filed a notice with U.S. District Court in New Mexico.

It disclosed that a federal agent had obtained a second search warrant earlier this month for the phone of Mr. Eastman — the first time Mr. Windom’s name has appeared on a public case filing in a Trump-related matter.

In the wake of those search warrants, the Justice Department set up a so-called filter team to deal with any potentially privileged information gleaned from those warrants, according to the filing.

Previously, it had only been known that the department’s inspector general had obtained a search warrant for Mr. Eastman for a narrower internal department inquiry that had begun after the Jan. 6 riot.

In his public statements, Mr. Garland has exhibited an awareness of the extraordinary perils his department, and the country at large, face as investigators close in on a once and perhaps future presidential candidate whose popularity is firmly tied to his claim that he is being persecuted by the Washington establishment.

Last week, Mr. Garland sat in his conference room at the Justice Department, flanked by oil portraits of two predecessors he admires — Robert F. Kennedy and Edward H. Levi — to declare that no one, not even Mr. Trump, was “above the law.”

That statement, which he has made in public before, was widely disseminated on social media.

But just before that, Mr. Garland said something that, in some ways, better reflects his cautious approach to an investigation that he has characterized as both the biggest and most important in the department’s 152-year history.

“We have to hold accountable every person who is criminally responsible for trying to overturn a legitimate election, and we must do it in a way filled with integrity and professionalism, the way the Justice Department conducts investigations,” he said.

“Both of these are necessary in order to achieve justice and to protect our democracy.”

Michael S. Schmidt and Alan Feuer contributed reporting.