"It was personal and it was ugly and it was overwhelming," government prosecutor Leo Wise told the 12-member jury during closing arguments in the trial of the son, Hunter Biden, 54.
"But it was also necessary."
The federal government case, the first criminal trial of a US president's child, last week offered an intimate view of the younger Biden's years of struggle with alcohol and crack cocaine abuse, which prosecutors say legally precluded him from buying a gun.
Hunter Biden has pleaded not guilty to felony charges both of lying about his addiction when he filled out a government screening document for the Colt Cobra revolver and of illegally possessing the weapon for 11 days.
Wise said it did not matter if well-known people appeared in court or how they reacted to the evidence, a possible reference to first lady Jill Biden's attendance.
"None of that matters. What matters came from the witness stand," he said.
First lady Jill Biden attended Hunter Biden's trial in support of the president's son. (AP PHOTO)
Last week, 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 told the judge overseeing the case at a 2023 hearing that he has been sober since 2019.
Biden's lawyer Abbe Lowell told jurors during his opening statement that his client did not intend to deceive because he had been clean when he bought the gun and did not consider himself a drug user at the time.
The defence called three witnesses on Friday, including the gun shop owner and an employee and Hunter Biden's daughter Naomi, who said her father appeared to be doing well when she saw him during the weeks before and after he bought the gun.
The sentencing guidelines for the charges against Biden are 15 to 21 months but legal experts say defendants in cases similar to his often get shorter sentences and are less likely to be incarcerated if they abide by the terms of their pre-trial release.
