WILMINGTON, Del. — A sister who faced drug and credit card fraud charges. A childhood best friend who overdosed on heroin. A nephew who was a scholarship athlete who became addicted to oxycontin after an injury.

As lawyers for the government and those defending the president’s son sought Monday to narrow a field of more than 250 Delawareans to a jury of 12 and four alternates, they heard again and again about the toll that addiction had taken on many who would potentially hear a case that…