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.

Taking the stand as a prosecution witness, Hunter Biden's ex-wife Kathleen Buhle described how, after 25 years, their marriage deteriorated under the weight of his drug and alcohol addiction.

Buhle said she first learned of Hunter Biden's crack addiction when she discovered an empty crack pipe in an ash tray on their side porch the day after their anniversary in 2015. Hunter Biden was kicked out of the Navy in 2014 for testing positive for cocaine, and Buhle said ever since then she was "worried, scared" he would abuse drugs again.

When he was on crack, Buhle testified, "He was not himself … angry, short-tempered, acting in ways he wouldn't when he was sober."

She said she would find drug "remnants in little bags" and drug paraphernalia like "a broken crack pipe" -- often enough that she would search his car before allowing her daughters to use it.

In what could be a blow to one of Abbe Lowell's lines of defense, Buhle said Hunter Biden frequently interacted with friends and family, worked, and socialized while under the influence of crack cocaine -- and would often try to hide it from those close to him.

"Did you see him, for lack of a better word, function?" prosecutor Leo Wise asked.

"Yes," Buhle confirmed.