Wilmington, Delaware - Opening arguments began on Tuesday in the trial of Hunter Biden on gun charges, the first-ever prosecution of a child of a sitting US president.

Hunter Biden (54), the only surviving son of President Joe Biden, is charged with lying about his illegal drug use when buying a handgun in 2018, a felony.

A 12-member jury with four alternates was seated on Monday for the federal trial being held in the Biden hometown of Wilmington.

Expected to last one to two weeks, Hunter Biden's trial comes as his father is seeking re-election and just days after the conviction on business fraud charges of Donald Trump, the president's likely opponent in November.

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The proceedings, along with another trial in which Hunter Biden faces tax evasion charges in California, complicate Democrats' efforts to keep the focus on Trump, the first former president ever to be convicted of a crime.

Trump also faces three far more serious criminal cases, including for his alleged efforts to overturn the results of the 2020 presidential election.

First Lady Jill Biden was in court on Monday for jury selection and again for Tuesday's hearing, when one juror was dismissed from the panel as they could not commit to the full trial.

The president did not attend but said he and Jill were "proud" of Hunter Biden.

"As the President, I don't and won't comment on pending federal cases, but as a Dad, I have boundless love for my son, confidence in him, and respect for his strength," Biden said in a statement.

In addition to being a political distraction, Hunter Biden's legal woes have reopened painful emotional wounds for the family from his time as a drug addict.

His brother Beau died from cancer in 2015, and his sister Naomi died as an infant in a 1972 car crash that also killed their mother, Neilia, Joe Biden's first wife.

The Yale-trained lawyer and lobbyist-turned-artist is charged with falsely stating when buying a .38 caliber revolver in 2018 that he was not using drugs illegally.

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He is also charged with illegal possession of the firearm, which he had for just 11 days in October of that year.

Prosecutors are set to introduce often uncomfortable evidence linked to Hunter Biden's years as an addict. His defense team had fought to keep a number of images out of evidence, but on Tuesday, the judge ruled they could be used by prosecutors, CNN reported.

The president's son, who has written unsparingly about his addiction, will contend that at the moment he bought the revolver, he did not consider himself to be an addict. He has stated that he has been sober since 2019.

If found guilty, Hunter Biden could face 25 years in prison, although as a first-time offender, jail time is unlikely.

President Biden on Monday said his son's difficulties would resonate widely.

"Hunter's resilience in the face of adversity and the strength he has brought to his recovery are inspiring to us. A lot of families have loved ones who have overcome addiction and know what we mean," he said.

Hunter Biden has long been the target of hard-right Republicans, and Trump allies have investigated him at length in Congress on allegations of corruption and influence-peddling.

No charges have ever been brought.

Hunter Biden's business dealings in China and Ukraine have also formed the basis for attempts by Republican lawmakers to initiate impeachment proceedings against Biden. Those efforts, too, have gone nowhere.

The White House said last year that there would be no presidential pardon for Hunter Biden in case of a conviction.