Hunter Biden has arrived at the courthouse for the start of his federal gun trial this morning.

His stepmother, first lady Jill Biden, is attending the proceedings.

Two hundred and fifty Delaware residents have been summoned to the courthouse in downtown Wilmington, where they will face typical questions about their fitness to serve as jurors.

But because this is the trial of the son of a sitting president, there will be some novel topics covered during the jury selection process known as "voir dire."

Among the questions jurors will be asked: "If you were eligible to vote in any election(s) in which Joseph R. Biden was a candidate, would that fact prevent you from maintaining an open, impartial mind until all of the evidence is presented, and the instructions of the Court are given?"

And "Do you believe Robert Hunter Biden is being prosecuted in this case because his father is the President of the United States and a candidate for President?"

On the eve of trial, U.S. District Judge Maryellen Noreika threw a wrench in one of the key arguments attorneys for Hunter Biden were planning to advance, ruling that an annotated copy of the federal form Hunter Biden is accused of lying on would be excluded from evidence.

The original document, called an ATF Form 4473, was created in 2018 when Hunter Biden purchased the firearm. But in 2021, gun store employees made a copy that included some handwritten notes. Defense attorney Abbe Lowell contended that employees had "tampered with" the document, and that it raised questions about "who wrote what on the form, and when."

Lowell hoped his argument would undermine the credibility of some key government witnesses -- the people who sold Biden the gun -- and potentially create a reasonable doubt that Hunter Biden was the one who actually checked that box.

Attorneys for special counsel David Weiss' office have said the gun shop employees merely "annotated" the form and urged Noreika to prevent Lowell from introducing it into evidence.

Late Sunday, Noreika sided with Weiss.

Jury selection is scheduled to get underway today in the federal gun trial of Hunter Biden, who authorities say broke the law when he purchased a Colt revolver in 2018.

President Joe Biden's son faces two counts of making false statements while purchasing the firearm and a third count of illegally obtaining it while addicted to drugs.

Although the charges together carry a possible sentence of up to 25 years, legal experts say that, as a first-time and nonviolent offender, Hunter Biden would not likely serve time if convicted.

The trial, in Delaware federal court, is expected to last two to three weeks.

Hunter Biden's attorney sought to cast doubt on the government's narrative during his opening statement, claiming that Hunter Biden was not actively using drugs at the time of his gun purchase and therefore did not "knowingly" lie on the federal form barring drug users from procuring a firearm.

"He did not knowingly violate these laws," attorney Abbe Lowell said, since there was "nothing on the form about the definition of a user."

Lowell told the jury that Hunter Biden was using alcohol at the time of the gun purchase, but that his drug use "did not start until later."

The attorney said that while Hunter Biden was in Delaware, where he purchased the gun, his behavior was "totally inconsistent" with how he presented it when he was on drugs.

"He spoke with his father, his uncle, his daughters," Lowell said, suggesting they would have noticed if he was "smoking crack every 15 minutes," as he described in his 2021 memoir, "Beautiful Things."

"There is no such thing as a high-functioning crack addict," Lowell said.

Lowell told the jury that Hunter Biden had entered a 12-day rehab program in California before returning to Delaware in the fall of 2018, just a week before the gun purchase, shepherded by his "Uncle Jimmy Biden," who Lowell suggested will testify at trial.

Lowell also pushed back on one of the government's key pieces of evidence -- a text Hunter sent to his then-romantic partner Halle Biden days after purchasing the gun, in which he claimed to be "on a car" smoking crack. Prosecutors said this was evidence that he was using drugs at the time, but Lowell said that, "in reality, he did not want to see Hallie."

As part of the defense, Lowell also appeared to shift some blame to the owners and employees at the gun store where Hunter Biden purchased the gun, saying they "wanted to make a sale."

Lowell claimed that Hunter Biden first purchased a BB gun and a knife at the store, and only purchased the gun after they approached him.

"Hunter wouldn't have known what a speedloader was," said Lowell, who also claimed the salesman never "took Hunter through" the form to ensure he understood it.

"How quickly does a person check through those boxes?" Lowell asked jurors.

Lowell also pushed back on allegations involving the gun pouch that was found with the firearm after Hallie Biden threw the gun it in a dumpster. Prosecutors allege that the pouch had cocaine residue on it, but Lowell said it was never checked for fingerprints and called into question its chain of custody.

"Hunter has never asked anyone to excuse his mistakes," Lowell said, before asking jurors to find him not guilty.

As Lowell delivered his opening statement, first lady Jill Biden, Hunter Biden's wife Melissa Cohen Biden, and his half-sister Ashley Biden sat largely stoic in the gallery. Hunter Biden kept his eyes on Lowell and his hands clasped. Jurors paid close attention, with several taking notes.