Jordin Melgar-Salmeron was deported to El Salvador on May 7 despite an order from the U.S. Court of Appeals for the Second Circuit, New York, blocking it. The government has since denied that it violated the order, instead blaming the situation on a "confluence of administrative errors," according to a court filing last week.

Migrants are being detained by immigration agents in courthouse hallways nationwide, sometimes moments after pleading their cases, raising alarm among attorneys and advocates who say the practice is turning immigration courts from places of due process into zones of fear.