LOS ANGELES, United States: US President Joe Biden's son Hunter asked federal judges on Thursday to toss out gun and tax cases filed against him, citing a legal argument made by Donald Trump.

Hunter Biden, 54, was convicted in Delaware in June on federal gun charges in a historic first criminal prosecution of the child of a sitting US president.

He also faces tax evasion charges in California and is scheduled to go on trial in September.

In filings on Thursday with district court judges in Delaware and California, Hunter Biden's lawyers asked that the gun conviction be tossed out and the tax charges dismissed.

They cited a ruling from a district judge in Florida on Monday in a separate case involving Trump.

District Judge Aileen Cannon dismissed a criminal case charging Trump with mishandling top secret documents on the grounds that Jack Smith, the special counsel who brought the charges against the former president, was unlawfully appointed.

The gun and tax charges against Hunter Biden were also brought by a special counsel and the lawyers for the president's son said the charges against him should be dismissed for the same reason.

"The Attorney General relied upon the exact same authority to appoint the Special Counsel in both the Trump and Biden matters, and both appointments are invalid," said Abbe Lowell, one of Hunter Biden's lawyers.

"Different defendants but same constitutional flaws."

Smith, the special counsel in the Trump case, has appealed Cannon's ruling.

Hunter Biden was convicted last month on three felony counts stemming from his 2018 purchase of a handgun while addicted to crack cocaine.

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

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

The president's son, who has written unsparingly about his addiction, claimed that at the time he bought the revolver he did not consider himself to be an addict.

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 his father.

Those efforts, too, have not yielded results.

  - AFP