Hunter Biden walks back to the motorcade after visiting a jewelry store with his father US President Joe Biden in Greenville, Delaware, on December 18, 2023.
Hunter Biden walks back to the motorcade after visiting a jewelry store with his father US President Joe Biden AFP

A federal judge presiding over Hunter Biden's gun trial rejected one of his expert witnesses and blocked the defense team from using a key piece of evidence.

Judge Maryellen Noreika's order came on Sunday, dealing the defense team two huge setbacks just hours before the start of the trial.

Meanwhile, jury selection is set to start on Monday in the federal gun case against Hunter Biden, son of President Joe Biden, after a plea deal with prosecutors fell through, according to Associated Press.

Hunter, who spent the weekend with his father, faces three felony charges related to a 2018 firearm purchase. He had said in his memoir that he was battling a severe crack addiction at the time. The charges include lying to a federally licensed gun dealer, falsely claiming on the firearms application that he was not a drug user, and illegally possessing the gun for 11 days.

Hunter has pleaded not guilty, maintaining that he is being unfairly targeted by the Justice Department.

In a court order issued on Sunday, the judge first granted special counsel David Weiss's request to exclude one of Hunter's expert witnesses. The blocked testimony was to be provided by a Columbia University-based psychiatrist, who was prepared to challenge the prosecution's claim that Biden was aware of his addiction in 2018 when he purchased the firearm, which is the center of the indictment.

"The inadequacy of Defendant's expert disclosure for Dr. (Elie) Aoun leaves the government in the dark as to what his opinions about the facts of this case will be, thus rendering the government unable to prepare for trial," Judge Noreika wrote in the order.

The judge also ruled against allowing a key piece of evidence that Hunter's lawyers intended to use -- an altered version of the federal firearms form that Hunter filled when he bought the gun in 2018. This version, modified in 2021 by gun store employees, was intended to cast doubt on the credibility of those employees, who are expected to testify for the prosecution.

The defense argued that the altered form demonstrated political bias in the prosecution's case.

However, Judge Noreika deemed the altered form "irrelevant and inadmissible," criticizing the defense for advancing "conspiratorial" theories and "unsupported rhetoric" about the motivations of the Wilmington gun store employees.

"Any probative value it arguably has is substantially outweighed by a danger of unfair prejudice, confusion of issues, and misleading the jury," she wrote.

The judge added that any attempts by the defense to use the altered form to demonstrate the employees' alleged political bias would have been "unduly prejudicial and invites (jury) nullification."