Hunter Biden has become the first child of a sitting US president to be convicted after a jury took less than three hours to find him guilty in a gun crimes case that detailed his former addiction to cocaine.

President Joe Biden’s son faces up to 25 years in jail – although the sentence is likely to be much less as a first-time offender – for lying about his drug use when he illegally purchased a gun.

The three charges related to him buying a revolver from a Delaware gun shop in 2018.

Biden was charged with two counts of lying on a federal background check form about his drug use and one count of possessing a gun while addicted to illegal drugs.

The case had been playing out in Wilmington, Delaware, where government lawyers showed “grim” evidence of Biden’s years of struggle with alcohol and crack cocaine abuse.

Hunter Biden’s ex-wife, former girlfriend and sister-in-law testified for the prosecution about his drug use, telling jurors that they often found drugs and paraphernalia in his possession and were concerned at times about his spiralling addiction.

Hunter Biden’s daughter Naomi was among the defence witnesses and said her father appeared to be doing well when she saw him during the weeks before and after he bought the gun.

Biden, 54, lightly nodded his head after the verdict was read but otherwise showed little reaction.

He then patted his lawyer Abbe Lowell on the back and hugged another member of his legal team and left the courthouse without making a statement.

His father, Joe Biden, issued a statement saying he accepted the outcome of the case and would respect the judicial process as his son considers an appeal.

“As I said last week, I am the President, but I am also a dad,” Biden said.

“Jill and I love our son, and we are so proud of the man he is today. So many families who have had loved ones battle addiction understand the feeling of pride seeing someone you love come out the other side and be so strong and resilient in recovery.”

Special counsel David Weiss said after the verdict that Hunter Biden’s conviction was a reminder that no one was above the law.

“Everyone must be accountable for their actions, even this defendant,” Weiss said.

Jurors found Hunter Biden guilty of lying to a federally licensed gun dealer, making a false claim on the application by saying he was not a drug user and illegally having the gun for 11 days.

Weiss is an appointee of former president Donald Trump.

He has also charged Hunter Biden with three felony and six misdemeanour tax offences in California, alleging he failed to pay $US1.4 million ($2.1 million) in taxes between 2016 and 2019 while spending millions on drugs, escorts, exotic cars and other high-ticket items.

Biden has pleaded not guilty to those charges.

A trial is scheduled for September 5 in Los Angeles.

The Delaware trial included prosecution testimony by Hunter Biden’s ex-wife, former girlfriend and sister-in-law, who gave firsthand accounts of his spiralling addiction in the weeks before and after he bought the gun in October 2018.

Prosecutors also showed text messages, photos and bank records that they said showed Biden was deep in the throes of addiction when he bought the gun and knowingly broke the law by answering “no” to being a drug user on a government screening form.

Biden’s lawyers sought to show he was not using drugs when he bought the gun and did not intend to deceive because he did not consider himself a drug user when he filled out the form.

The sentencing guidelines for the gun-related charges against Biden are 15 to 21 months in jail. But legal experts say defendants in similar cases often get shorter sentences and are less likely to be incarcerated if they abide by the terms of their pre-trial release.

First lady Jill Biden, the President’s brother James and other family members watched from the first row of the courtroom as the defence rested its case on Monday without calling Biden to the witness stand.

The first lady has been in court almost every day since the trial began last week.

-with AAP