Judge Hannah Dugan was arrested on suspicion that she “intentionally misdirected federal agents away from” an immigrant being pursued by the authorities, the F.B.I. director said in a social media post.
F.B.I. agents arrested a county judge in Milwaukee on Friday on charges of obstructing immigration agents by steering an undocumented immigrant through a side door in her courtroom while the agents waited in a public hallway to apprehend him.
The arrest of a sitting state court judge is a major escalation in the Trump administration’s battle with local authorities over deportations. The administration has demanded, under threat of investigation or prosecution, that local officials assist federal efforts to deport millions of undocumented immigrants.
Charging documents describe a confrontation last Friday at Judge Dugan’s courthouse, in which federal agents say she was “visibly upset and had a confrontational, angry demeanor” when a group of immigration, D.E.A. and F.B.I. agents came to arrest Eduardo Flores-Ruiz, a citizen of Mexico who was in her courtroom to face misdemeanor criminal charges.
According to the criminal complaint, the judge confronted the agents and told them to go talk to the chief judge of the courthouse. She then returned to her courtroom.
“Despite having been advised of the administrative warrant for the arrest of Flores-Ruiz, Judge Dugan then escorted Flores-Ruiz and his counsel out of the courtroom through the ‘jury door,’ which leads to a nonpublic area of the courthouse,” said the complaint, which was written by an F.B.I. agent.
The judge was charged with obstructing a proceeding of a federal agency and concealing an individual to prevent his discovery and arrest.


