Inside a Virginia courthouse, three immigration agents in plainclothes — one masked — detained a man who had just had misdemeanor assault charges dismissed. They declined to show identification or a warrant to the man, and one threatened to prosecute horrified witnesses who tried to intervene, cellphone video shows. The flurry of immigration enforcement at courthouses around the country in the past month — already heavily criticized by judicial officials and lawyers — has renewed a legal battle from President Donald Trump's first term as advocates fear people might avoid coming to court.