WASHINGTON — The U.S. Marshals Service lacks the capability of adequately detecting threats against federal judges across the nation and uses outdated security equipment to protect judges’ homes, the Justice Department’s inspector general said Wednesday.The report on the agency’s judicial security program comes nearly a year after a gunman killed the 20-year-old son of a federal judge and wounded her husband at their New Jersey home after posing as a delivery driver.The inspector general’s report highlights serious …