Specifically, the complaint says Dugan assisted Eduardo Flores-Ruiz, a Mexican immigrant, avoid being arrested by federal immigration officials at the Milwaukee County Courthouse after he appeared in her courtroom for a pre-trial conference on April 18.

The arrest marks a significant escalation in the Trump administration's crackdown on immigration, as well as in its battles with judges across the country.

The FBI has arrested a Milwaukee judge accused of helping a man evade immigration authorities. Friday's arrest escalates a clash between the Trump administration and local authorities over the president’s sweeping immigration crackdown.