Attorney General William Barr on Wednesday defended the Justice Department’s move to intervene in a defamation lawsuit against President Donald Trump, even as experts were skeptical of the federal government’s effort to protect the president in a seemingly private dispute. The department’s move is likely to have an ancillary benefit for Trump in delaying the case, but administration lawyers have a tough task at hand trying to argue that the president was acting in his official capacity when he denied Carroll’s allegations last year, experts say.