Judge Maryellen Noreika, in her initial instructions to jurors, explained how they are to apply the law to the facts of the case for the three criminal counts Hunter Biden faces.

"You must not attach any significance to the fact that the defendant did not testify," she read aloud in the courtroom, after the defense decided not to call Hunter Biden to the stand.

The judge defined "knowingly," the central term by which jurors must determine if Hunter Biden bought the gun at the center of the case "knowing" he was an addict or user of drugs, after he stated on the gun-purchase form that he was not.

Closing arguments are scheduled to begin at 12:05 p.m. ET, after which the judge will give the jury her final instructions and their deliberations will begin.

Closing arguments will begin at about noon ET after Hunter Biden chose not to testify in his federal gun case.

The defense rested without him taking the stand, after which prosecutors presented a brief rebuttal case, then the judge gave the jury their initial instructions.

Following the prosecution's rebuttal case, the judge read the jury their initial instructions.

Court is then expected to break for lunch, with closing arguments currently scheduled for the afternoon.

The judge will then give the jury their final instructions before they begin deliberations.

The government rested its rebuttal case after a brief cross-examination of FBI special agent Erika Jensen, who testified about location and text message data relevant to the case.

Attorneys then gathered for another sidebar conference.

Under cross-examination from defense attorney Abbe Lowell, Hunter Biden's former girlfriend Hallie Biden said some of her memories of their interactions from the time of the gun purchase are vague.

Lowell began his questioning by saying he understood that it was a "fairly upsetting" period and that "being here is no picnic either."

Hallie Biden conceded that "it's difficult to recall" exactly where Hunter was at specific moments or whether he was where he suggested he was, at one point saying that "it's all kind of vague."

"Reconstructing this is not easy?" Lowell asked her.

"Correct," she replied.

Hallie Biden, the widow of Hunter Biden's late brother Beau Biden, testified that the "remnants" of crack she found in Hunter Biden's car on Oct. 23, 2018 -- the day she discovered then discarded the firearm -- could have been from weeks or months earlier.

"You didn't see him doing drugs or alcohol" the day you discarded the gun, Lowell inquired.

"Correct," she said.

At one point Lowell's cross-examination descended into a bit of chaos as both Lowell and Hallie Biden struggled to follow the proper protocols to get her text messages admitted into evidence.

"So far so good," Abbe said at one point.

"Well, no," prosecutor Leo Wise objected.

Jurors rubbed their eyes and gazed around as the back-and-forth continued, with the courtroom bursting into laughter on several occasions. At one point, Hallie Biden appeared to look over at her fiancé sitting in gallery, shrugging her shoulders and appearing to mouth the words "I don't know."

Court was subsequently recessed for lunch.