Donald Trump became the first former president to face a judge on federal charges as he pleaded not guilty in a Miami courtroom Tuesday to dozens of felony counts accusing him of hoarding classified documents and refusing government demands to give them back.

The history-making court date, centred on charges that Trump mishandled government secrets that as commander-in-chief he was entrusted to protect, kickstarts a legal process that could unfold at the height of the 2024 presidential campaign and carry profound consequences not only for his political future but also for his own personal liberty.

Trump approached his arraignment with characteristic bravado, posting social media broadsides against the prosecution from inside his motorcade en route to the courthouse and insisting as he has through years of legal woes that he has done nothing wrong and was being persecuted for political purposes.?

But inside the courtroom, he sat silently, scowling and arms crossed as a lawyer entered a not guilty plea on his behalf in a brief arraignment that ended without him having to surrender his passport or otherwise restrict his travel.

The arraignment, though largely procedural in nature, was the latest in an unprecedented public reckoning this year for Trump, who faces charges in New York arising from hush money payments during his 2016 presidential campaign as well as ongoing investigations in Washington and Atlanta into efforts to undo the results of the 2020 race.

He has sought to project confidence in the face of unmistakable legal peril, attacking the Justice Department special counsel who filed the case as "a Trump hater", pledging to remain in the race and scheduling a speech and fundraiser for Tuesday night at his Bedminster, New Jersey, club.?

He stopped on his way out of Miami at Versailles, an iconic Cuban restaurant in the city's Little Havana neighbourhood where supporters serenaded Trump, who turns 77 years old on Wednesday, with "Happy Birthday".

Even so, the gravity of the moment was clear.

Until last week, no former president had ever been charged by the Justice Department, let alone accused of mishandling top-secret information.?

The indictment unsealed last week charged Trump with 37 felony counts -- many under the Espionage Act -- that accuse him of illegally storing classified documents in his bedroom, bathroom, shower and other locations at Mar-a-Lago and trying to hide them from the Justice Department as investigators demanded them back.?

The charges carry a yearslong prison sentence in the event of a conviction.

Trump has relied on a familiar playbook of painting himself as a victim of political persecution. But Attorney General Merrick Garland, an appointee of President Joe Biden, sought to insulate the department from political attacks by handing ownership of the case to a special counsel, Jack Smith, who on Friday declared, "We have one set of laws in this country, and they apply to everyone."

Smith attended Tuesday's arraignment, sitting in the front row behind his team of prosecutors.

The court appearance unfolded against the backdrop of potential protests, with some high-profile backers using barbed rhetoric to voice support. Trump himself encouraged supporters to join a planned protest Tuesday at the courthouse. Though city officials said they prepared for possible unrest around the courthouse, there were little signs of significant disruption.

While Trump was not required to surrender a passport -- prosecutor David Harbach said he was not considered a flight risk, a likely recognition of his status as a presidential candidate -- he was directed to not have any personal contact with any witnesses in the case. That includes Walt Nauta, his valet and close aide, who was indicted last week on charges that he moved boxes of documents at Trump's direction and misled the FBI about it. He did not enter a plea Tuesday because he did not have a local lawyer with him.

The magistrate judge who presided over the arraignment directed Trump not to discuss the case with any witnesses, including Nauta, but said they can discuss work.

Even for a man whose post-presidential life has been defined by criminal investigations, the documents probe had long stood out both because of the volume of evidence that prosecutors had seemed to amass and the severity of the allegations.

A federal grand jury in Washington had heard testimony for months, but the Justice Department filed it in Florida, where Trump's Mar-a-Lago resort is located and where many of the alleged acts of obstruction occurred. Though Trump appeared Tuesday before a federal magistrate, the case has been assigned to a District Court judge he appointed, Aileen Cannon, who ruled in his favour last year in a dispute over whether an outside special master could be appointed to review the seized classified documents. A federal appeals panel ultimately overturned her ruling.

It's unclear what defences Trump is likely to invoke as the case moves forward. Two of his lead lawyers announced their resignation the morning after his indictment, and the notes and recollections of another attorney, M Evan Corcoran, are cited repeatedly throughout the 49-page charging document, suggesting prosecutors envision him as a potential key witness.

The Justice Department unsealed Friday an indictment charging Trump with 37 felony counts, 31 relating to the willful retention of national defence information. Other charges include conspiracy to commit obstruction and false statements.

The indictment alleges Trump intentionally retained hundreds of classified documents that he took with him from the White House to Mar-a-Lago after leaving office in January 2021.?

The material he stored, including in a bathroom, ballroom, bedroom and shower, included material on nuclear programs, defence and weapons capabilities of the US and foreign governments and a Pentagon "attack plan", prosecutors say.

Beyond that, prosecutors say, he sought to obstruct government efforts to recover the documents, including by directing personal aide Walt Nauta -- who was charged alongside Trump -- to move boxes to conceal them and also suggesting to his own lawyer that he hide or destroy documents sought by a Justice Department subpoena.