WASHINGTON - Aileen M. Cannon was not yet 40 years old when the federal prosecutor won decisive bipartisan support in a bitterly divided U.S. Senate to claim her seat on the district court in South Florida, in what would be President Donald Trump's final push to fill the federal bench with young conservative lawyers before leaving the White House.

Her profile soared this week after she intervened in the Justice Department investigation into Trump's possible mishandling of classified information and agreed to grant his request for an independent review of the material that FBI agents have seized. Trump sought the appointment of what's known as a special master to assess whether the government took anything from his Florida residence that may be protected by attorney-client privilege or his status as a former president.

Cannon's controversial ruling, which she called necessary to "ensure at least the appearance of fairness and integrity under the extraordinary circumstances," temporarily bars investigators from using the documents removed last month from his Mar-a-Lago residence. The order has been criticized by legal experts for seeming to extend special treatment to Trump and for disrupting the probe before anyone has been charged with a crime. On Thursday, the government said it would appeal Cannon's decision.

With less than two years on the bench, she does not have an extensive record to review. The Trump dispute has put a spotlight on her while presenting untested questions about the extent to which assertions of executive privilege - usually invoked by sitting presidents to shield sensitive communications from disclosure - may be applied to past occupants of the White House in conflict with their successors.

Cannon did not respond to a request for comment.

Former senator Russ Feingold - who leads the liberal American Constitution Society, which closely tracks judicial nominations - said Trump and his Republican allies in the Senate sought out judicial nominees like Cannon, showing an "overwhelming preference" for individuals often lacking the experience "previously considered necessary to sit on the bench."

"We're now seeing the impact of this, with an alarming disregard of the rule of law by some," he said in a statement.

Sen. Marco Rubio, the Florida Republican whose office asked Cannon to apply for the position in 2019, rejected any suggestion that her decision in the classified-documents case was politically motivated and noted the support Cannon received from Senate Democrats. Twelve voted in favor of her confirmation.

"Judge Cannon is a great judge who I am very proud to have enthusiastically supported," Rubio said in a statement. "The attacks against her are just the latest example of hypocrisy from leftists and their media enablers who believe the only time it is acceptable to attack a judge is if that judge rules against what they want."

Cannon's confirmation hearing took place six months into the coronavirus pandemic, in July 2020, and she appeared before the Senate Judiciary Committee by Zoom. She had the backing of the Cuban American Bar Association, which praised her "temperament and academic credentials" and pointed to her "legal mind and demeanor." By choosing Cannon, the group told lawmakers, "you enhance the diversity on the bench and help appoint a great candidate for the position."

In follow-up questions, Democrats pressed Cannon about her record as a prosecutor, her judicial philosophy and her membership in the Federalist Society, the conservative organization that played a major role in advising Trump on his judicial picks. In response to Sen. Cory Booker, D-N.J., Cannon said she considers herself an "originalist" and a "textualist," referring to methods of legal interpretation that look to the general understanding of the Constitution at the time it was written, an approach most often associated with the late conservative Supreme Court justice Antonin Scalia.

Cannon quoted Elena Kagan, the liberal justice who quipped at her confirmation hearing, "We are all originalists."

Sen. Dianne Feinstein, D-Calif., asked Cannon specifically whether she had any discussions during the nomination process about "loyalty to President Trump."

"No," Cannon responded in writing.

She was one of 14 nominees confirmed after the November 2020 election, amid the tumultuous aftermath of Trump's defeat, an appointment that will now stand as a notable part of his legacy. Over four years in the White House, he installed more than 200 federal judges, including three Supreme Court justices.

Until last week, one of Cannon's most high-profile cases in 20 months on the bench involved sentencing a man who pleaded guilty to making death threats against House Speaker Nancy Pelosi, D-Calif., and Rep. Alexandria Ocasio-Cortez, D-N.Y. In a separate case in April, one of Cannon's new judicial colleagues accused Trump of judge-shopping for Cannon by filing a lawsuit against Hillary Clinton and former FBI agents in the court's Fort Pierce division, where Cannon is the only federal judge. Trump's lawsuit instead landed with a judge who is a nominee of Bill Clinton. He rejected Trump's move to disqualify him from the case, pointing out in a footnote that when Trump is in court "before a judge that he himself appointed, he does not tend to advance these same sorts of bias concerns."

Cannon, now 41, was born in Colombia, the daughter of a Cuban immigrant mother, and grew up in Miami. She spoke at her confirmation hearing about the lasting influence of her mother, who at age 7 "had to flee the repressive Castro regime in search of freedom and security."

"Thank you for teaching me about the blessings of this country and the importance of security and the rule of law for generations to come," Cannon said.

As an undergraduate at Duke University, she worked one summer for the Spanish-language newspaper Nuevo Herald, writing on diverse topics including Flamenco and prenatal yoga. At the University of Michigan Law School, she joined the Federalist Society, because, as she explained in response to Senate questions, she appreciated the "diversity of legal viewpoints" and discussion of the "limited role of the judiciary to say what the law is - not to make the law."

Before joining the bench, Cannon spent much of her career in the courtroom as a litigator. She was a law clerk for appeals court judge Steven M. Colloton, who was on Trump's list of potential Supreme Court picks, and an associate for three years in D.C. at the law firm Gibson, Dunn & Crutcher.

In 2013, as a new prosecutor in the U.S. attorney's office in South Florida, Cannon handled major crimes, including drug, firearm, and immigration cases. Soon after she moved to the appellate division, Cannon was assigned to defend the government's conviction in a large-scale, complex fraud case. She was up against an experienced appellate lawyer and appearing before a three-judge panel at the U.S. Court of Appeals for the 11th Circuit.

Richard Klugh, the veteran lawyer on the other side, was impressed.

"She was coming in against an old hand with a tremendously complicated record in an important case, but she seemed to handle it with ease," Klugh said in an interview. "She's quick, talented and bright. There's no getting around it. She's very effective."

Cannon prevailed, sustaining the conviction of a Florida lawyer in the life insurance scheme that affected thousands of investors.

Howard Srebnick, an attorney in Miami who attended the same high school as the judge, also was on the opposing side during Cannon's tenure as a prosecutor and now has a case pending before her.

In court, Cannon is polite and process-oriented, he said, asking a lot of questions while making sure litigants can fully air their views. Srebnick submitted a letter to the Senate in support of Cannon's nomination, signed by more than a dozen alumni of the private Ransom Everglades High School who also are attorneys.

She has "strength of character," the letter said, characterizing Cannon as "personable and trustworthy, a genuinely caring person who treats others as she would want to be treated herself."

In June, Cannon ruled against Srebnick's client, upholding the government's decision to freeze the defendant's bank account in a Medicare fraud case.

"She clearly spent considerable time and thought in deciding the question presented," Srebnick said. "We just disagree."

Srebnick, however, said that he agrees with Cannon's decision to appoint a special master in the Trump case even though the Justice Department has claimed to have already set aside potentially privileged records.

"She is spot-on correct that a special master, not a government-led filter team, should be handling those materials," Srebnick said. "No one from the government should be looking at a client's communications with counsel."

Cannon's ruling may not be the final word. The Justice Department on Thursday asked the judge to reconsider and temporarily suspend part of her order before it formally asks the appeals court to step in.

The Washington Post's Magda Jean-Louis contributed to this report.