Hunter Biden has filed a legal motion asking that the three felony gun charges against him be dismissed. The president’s son argues that a plea deal he was offered — and that a judge threw out — is actually binding, as it was signed by both Mr. Biden and his prosecutors.

In a new court filing, Mr. Biden’s attorney, Abbe Lowell, states that the plea deal “that both parties signed remains in force, and he will seek to dismiss the Indictment against him pursuant to the immunity provisions” of that deal. 

Mr. Lowell and Special Counsel David Weiss — who, in his capacity as the United States attorney for Delaware, has been investigating the first son since 2018 — negotiated an agreement earlier this year that would have allowed Mr. Biden to plead guilty to two misdemeanor counts of “willful” federal income tax evasion.

The agreement also would have placed Mr. Biden in what is called a pretrial diversion program that would have allowed the first son to avoid  a felony conviction for illegally purchasing a firearm in 2018. Instead, Mr. Biden would be expected to attend drug rehab and receive counseling.

The plea agreement, which was made public in August, described the fraud Mr. Biden committed in order to purchase the handgun — a Colt Cobra .38 Special revolver — on October 12, 2018, amid a debilitating drug and alcohol addiction. 

The agreement described how a few days after its purchase, the firearm “was found in Biden’s vehicle along with drug remnants and paraphernalia” and “was subsequently discarded in a trashcan outside a supermarket in Greenville, Delaware, and later recovered by law enforcement.” Politico has reported that the gun was discovered in Mr. Biden’s pickup truck by his then-girlfriend Hallie, who was also his elder brother Beau’s widow. She threw out the gun in a garbage bin at Wilmington.

The gun charges filed against Mr. Biden could mean years in prison, though legal observers say that few first-time offenders with no criminal records end up serving prison time.

Had the pretrial diversion program gone into effect as part of the plea deal, Mr. Biden would have taken frequent drug tests for two years while forever giving up his right to own a firearm. The diversion agreement, which is typically deployed for those who commit nonviolent offenses and do not have criminal pasts, states that “the United States agrees not to criminally prosecute Biden … for any crimes encompassed.” As long as he adhered to the agreement, he would be free from any and all criminal penalties for any past conduct.

The agreement continues, stating that it “does not provide any protection against prosecution for any future conduct by Biden or by any of his affiliated businesses.” 

The judge who will preside over Mr. Biden’s looming criminal trial, Maryellen Noreika, is the same one who refused to accept the “sweetheart plea deal,” as Republicans call it, that Mr. Weiss offered in July. 

Judge Noreika declined to accept the deal after a surprisingly chaotic hearing on July 26 during which the agreement fell apart entirely. The most pressing issue for Judge Noreika was the pretrial diversion program Mr. Biden would have entered, which included the statement that he would be immune for all past crimes.

She asked both the prosecution and the defense if he would be immune from charges of violating the Foreign Agents Registration Act, for one. The two sides did not agree if he was, in fact, immune from future charges. 

This led Judge Noreika to force both parties to quickly hash out the final agreement, though they eventually reached an impasse in negotiating a new deal, leading Mr. Weiss to withdraw the charges, but not before both the prosecution and the defense had signed on the dotted line. Judge Noreika agreed with Mr. Weiss in August and dismissed all charges, allowing the special counsel to charge the first son with three counts of lying on official paperwork in order to purchase the gun.