Wilmington (United States) (AFP) - Joe Biden's son Hunter goes on trial Monday on gun charges, the first prosecution in US history for the child of a sitting president -- just as the Democratic leader is seeking to accelerate his campaign for reelection.

The 54-year-old denies three felony counts stemming from his purchase of a .38-caliber Colt Cobra revolver in 2018 when, by his own admission, he was heavily addicted to drugs.

The Yale-trained lawyer and lobbyist-turned-artist has been plagued by legal troubles and controversies that have been a drag on his father's campaign, mostly connected to alcoholism and crack cocaine addiction.

In the latest chapter in his troubled life, Hunter Biden will be tried in the family's hometown of Wilmington, Delaware, on two counts of making false statements on paperwork for the gun purchase that he was not using drugs illegally.

He faces a third charge that he illegally possessed the gun -- which he had for only 11 days in October 2018.

The prosecution is a public relations test for the Democrats, coming just days after another historic event -- Republican White House nominee Donald Trump becoming the first former US president to be criminally convicted. 

'Smoking crack'

Biden campaign aides face the challenge of ensuring that daily responses to journalists' questions about the trial do not force Trump's own legal battles out of the headlines.

If found guilty, Hunter Biden could in theory face 25 years in prison, though in practice such offenses, if not accompanied by other charges, are seldom punished by jail time.

Jurors will hear about the defendant's excessive drug use as prosecutors run through the series of events that led to him buying the firearm in Delaware before it was thrown into a grocery store trash can by his girlfriend.

The younger Biden, who says he has been sober since 2019, chronicled his longtime struggles with drug addiction in his 2021 memoir "Beautiful Things" -- writing in one eye-watering extract that he was "smoking crack every 15 minutes."

The book is almost certain to be brought up at trial, with prosecutors expected to lean in on sections in which Biden describes being an addict for four years up to March 2019.

The defense team has pushed for narrow definitions of the terms "addict" and "user" and requested instructions requiring an acquittal if the jury determines that the defendant did not consider himself to fit those definitions.

"The terms 'user' or 'addict' are not defined on the form and were not explained to him," his lawyer Abbe Lowell wrote in court documents.

"Someone, like Mr. Biden who had just completed an 11-day rehabilitation program and lived with a sober companion after that, could surely believe he was not a present tense user or addict."

The case comes with Republicans pursuing an impeachment inquiry in Congress into what they claim is a Biden family criminal conspiracy, although they have provided no evidence that the president did anything wrong.

Republican politicians have accused Hunter Biden of engaging in corrupt business practices in China and Ukraine but he has not been charged with any crimes related to his foreign business dealings.

The president has repeatedly said he stands by his son and loves him for his attempts to recover from drug addiction, while the White House has not commented on the investigation itself.

Prosecutors have said they expect to take three days to present their case, and the entire trial will likely last about two weeks.

Hunter Biden faces separate tax evasion charges in his home state of California, in a case set to go to trial later in the year.