The federal judge overseeing Hunter Biden’s gun trial dealt his defense two setbacks Sunday, on the eve of jury selection, by blocking one of his expert witnesses and excluding a key piece of evidence the president’s son hoped to use.

The president's son will stand trial on federal charges of illegally possessing a firearm after allegedly lying about his status as a drug user when purchasing a pistol in 2018. He will become the first child of a sitting U.S. president to be criminally tried when jury selection begins on Monday.