Over his two years as the nation's number two law enforcement official, Rosenstein has been hit with a barrage of partisan criticism from both sides of the aisle -- including from the man who appointed him, President Trump.
“He’s faced criticism from all corners but has proven remarkably unflappable,” said Attorney General Bill Barr, speaking just before Rosenstein, told a crowd of hundreds gathered in the Justice Department’s Great Hall.
Rosenstein used his speech to state repeatedly his belief that the Justice Department should stay independent from the daily political battles in Washington, saying, "This department stands apart from politics." He made no direct reference to the criticisms he faced during his time overseeing Mueller's investigation.
"For us, the rule of law is not just a talking point," he said. "Many people have the luxury of dismissing facts that are inconsistent with their pre-existing beliefs, but we face the exacting scrutiny of a federal courtroom."
At one point Rosenstein seemed to take a veiled shot at former FBI Director James Comey, criticizing officials he said "trade virtue for the appearance of virtue" by departing from long-held DOJ traditions.
"We should exercise caution whenever unpleasant circumstances tempt us to disregard timeless principles," Rosenstein said, echoing a critique he leveled at Comey in his infamous memo the White House misleadingly used to justify Comey's firing. "It is most important to follow the rules when the stakes are highest. Sticking with traditions is usually the best course, not always, but usually."
In closing his speech, Rosenstein told the audience, "I leave here confident that justice is in good hands, in your hands."
Former Attorney General Jeff Sessions, who attended the ceremony as a special guest, offered the most direct defense of Rosenstein's role in Mueller's appointment.
"Rod, you did your duty as it fell upon you,” Sessions said. “You didn’t ask for it—that’s for sure... You have honorably overseen this process, which has affirmed the rule of law and achieved a degree of justice.”
Barr, on the other hand, channeled the media commentary surrounding his controversial press conference prior to the release of the Mueller report to get some laughs from the crowd.
"There's been a debate raging for the last few months and I think we have to get it resolved and decided tonight, and that is, which one of us is capable of the most deadpan expression?" Barr joked, calling Rosenstein over to stand beside him. "Now I know this is a little unfair because I do my best work in the hearing -- congressional hearings. Rod does his best one standing behind the attorney general at a press conference. So what do you say, is it Rod or me?"
Barr also used the speech to slip in a quick joke about the House Judiciary Committee's contempt proceedings on Wednesday, his first public remarks about the vote.
"I'll tell you now, the attorney general job is a lot different also," Barr said. "You like records, this must be a record of [an] attorney general being proposed for contempt within 100 days of taking office."
Other notable attendees at the ceremony included former White House counsel Don McGahn, current White House counsel Emmet Flood, White House Counselor Kellyanne Conway and former acting Attorney General Matt Whitaker.
Rosenstein's career has spanned three decades across multiple levels of the criminal justice system.
Comey's firing followed by the recusal of Sessions in the Russia investigation prompted Rosenstein's appointment of Robert Mueller as special counsel, a decision that would go on to largely define the remainder of his time as the nation's number two law enforcement official.
Lawmakers from both parties have at various points have cast Rosenstein as a villain.
House Republicans threatened Rosenstein with impeachment over his refusals to hand over classified documents relating to the origin of the investigation into Trump's campaign. A New York Times story from from late 2018 that Rosenstein once suggested the possibility of surreptitiously recording President Trump and enlisting Cabinet members to remove him from office by using the 25th Amendment further fueled calls from Republicans for Trump to oust him.
“I never pursued or authorized recording the President and any suggestion that I have ever advocated for the removal of the President is absolutely false," Rosenstein said in response to the story at the time.
In contrast, Democrats and former law enforcement officials have accused Rosenstein of not standing up enough to the president's frequent attacks against the DOJ and FBI, along with his decision to praise the president in his resignation letter.
"I am grateful to you for the opportunity to serve; for the courtesy and humor you often display in our personal conversations and for the goals you set in your inaugural address," Rosenstein wrote.
Just months earlier, Trump defended his decision to tweet out a picture showing Rosenstein behind bars along with a host of other political figures and other law enforcement officials.
"Accomplished people lacking inner strength can’t resist the compromises necessary to survive Mr. Trump and that adds up to something they will never recover from," Comey wrote in a recent New York Times op-ed in reference to Rosenstein and Barr. "Of course, to stay, you must be seen as on his team, so you make further compromises. You use his language, praise his leadership, tout his commitment to values."
Democrats have also recently raised questions over Rosenstein's decision not to recuse from the obstruction case against President Trump despite his role as a key witness to several of the episodes cited by Mueller's investigators.
In one contentious exchange during Barr's testimony to the Senate last week, Sen. Kamala Harris, D-Calif., pressed whether Rosenstein had been cleared by DOJ ethics officials to participate in the decision. Barr said Rosenstein had been cleared at the start of the investigation and dismissed questions that his role as a witness should mean he should have had his recusal re-evaluation.
It's unclear whether lawmakers plan to call Rosenstein to personally testify about the investigation following his official exit from the department on Saturday.
Jeffrey Rosen, a former lawyer who served as Deputy Secretary of Transportation, was nominated by President Trump to replace Rosenstein and is expected to face a confirmation vote before the Senate sometime next week.