United States President Joe Biden has pardoned his son Hunter ahead of his sentencing on gun and tax convictions despite a previous pledge not to use his presidential powers to grant him clemency.

Biden said on Sunday that his son had been “singled out” and “selectively, and unfairly” prosecuted due to his family name.

“There has been an effort to break Hunter – who has been five and a half years sober, even in the face of unrelenting attacks and selective prosecution,” Biden said in a statement released by the White House.

“In trying to break Hunter, they’ve tried to break me – and there’s no reason to believe it will stop here. Enough is enough.”

Biden added that throughout his career he had followed the “simple principle” of telling the American people the truth.

“Here’s the truth: I believe in the justice system, but as I have wrestled with this, I also believe raw politics has infected this process and it led to a miscarriage of justice – and once I made this decision this weekend, there was no sense in delaying it further,” Biden said.

“I hope Americans will understand why a father and a President would come to this decision.”

Biden’s announcement comes weeks before Hunter Biden was set to face sentencing for a string of felonies related to making a false statement about his drug use during a gun background check and failing to pay at least $1.4m in taxes.

The outgoing president’s decision is likely to stoke debate about the independence of the US justice system, which is already in the spotlight amid warnings by critics that President-elect Donald Trump intends to use law enforcement agencies stacked with loyalists to target his political rivals.

Trump, who faced a string of criminal cases before his re-election all but assured that he will not suffer serious legal consequences, blasted the pardon as an abuse of power.

“Does the pardon given by Joe to Hunter include the J-6 Hostages, who have now been imprisoned for years?” Trump said on his social media platform Truth Social, referring to people convicted of crimes related to the January 6, 2021 riot at the US Capitol.

“Such an abuse and miscarriage of Justice!”

The younger Biden had faced a maximum of 25 years in prison in the tax case and 17 years in the firearms case, though he would have almost certainly received much less severe punishment under federal sentencing guidelines.

Special counsel David Weiss, who was appointed by Attorney General Merrick Garland to probe allegations against Hunter Biden, brought the charges after an earlier plea deal collapsed under scrutiny from a judge.

In justifying his decision, Biden said that people are “almost never” brought to trial for wrongly filling out a gun purchase form and that those who pay their taxes late usually receive “non-criminal resolutions”.

The president said that Republicans, who cited Hunter Biden’s overseas business activities in a since-abandoned impeachment effort, had used his son’s troubles to damage him and oppose his election.

“Then, a carefully negotiated plea deal, agreed to by the Department of Justice, unraveled in the court room – with a number of my political opponents in Congress taking credit for bringing political pressure on the process,” Biden said.

“Had the plea deal held, it would have been a fair, reasonable resolution of Hunter’s cases.”

Biden’s pardon covers not only his son’s tax and firearms convictions but also any other offences he has “committed or may have committed or taken part in during the period from January 1, 2014 through December 1, 2024”.

In June, Biden had flatly ruled out the possibility of granting his son a pardon or commuting his sentence.

“I said I will abide by the jury decision. I will do that and I will not pardon him,” Biden had said.

The White House had reiterated Biden’s intention not to pardon his son as recently as November 8, when press secretary Karine Jean-Pierre told reporters: “Our answer stands, which is no.”

In a statement on Sunday, Hunter Biden said that mistakes he had made in the throes of addiction had been “exploited to publicly humiliate and shame me and my family for political sport”.

“In recovery we can be given the opportunity to make amends where possible and rebuild our lives if we never take for granted the mercy that we have been afforded,” he said.

“I will never take the clemency I have been given today for granted and will devote the life I have rebuilt to helping those who are still sick and suffering.”

Under the US Constitution, presidents have almost unlimited power to grant clemency to people convicted of federal crimes.

US presidents have used pardons to benefit family members and political allies in the past.

Shortly before the end of his first term, Trump pardoned Charles Kushner, the father of his son-in-law, Jared Kushner, after he did jail time for convictions for tax evasion, illegal campaign contributions and witness tampering.

In 2001, former US President Bill Clinton pardoned his half-brother Roger Clinton Jr, who served more than a year in prison in the 1980s after trying to sell cocaine to an undercover police officer.