WASHINGTON (AP) — The Justice Department on Friday escalated its legal battle against a contempt investigation targeting the Trump administration for its failure to comply with a judicial order regarding the deportation of Venezuelan migrants to El Salvador earlier this year.

The federal agency is appealing for a halt to the investigation, claiming Chief Judge James Boasberg has shown bias against the administration and that his conduct is undermining the separation of powers fundamental to the U.S. government.

This controversy has become a points of contention in the ongoing struggles between the judiciary and the executive over policies pursued during Donald Trump's presidency. The appeals court is being asked to act swiftly before Boasberg's scheduled hearing on Monday, where testimony from key whistleblowers, including a former Justice Department attorney, will be heard.

Justice Department officials argue that the inquiry amounts to a 'fishing expedition' and reflects an intention to drag out the proceedings unnecessarily. They contend that Boasberg's rulings have already demonstrated an inclination against the Trump administration, which could inhibit fair proceedings.

Adding to the complexity, Boasberg has asserted that his judicial authority allows him to pursue the contempt investigation, which seeks to determine if there is ample evidence to refer the matter for criminal prosecution.

Boasberg, appointed by former President Barack Obama, previously indicated that the Trump administration may have acted in bad faith by attempting to deport Venezuelan migrants despite a court order prohibiting such actions. The administration has denied any wrongdoing.

In a timely ruling, Boasberg has arranged for substantial witness testimonies, asserting that full transparency is vital to uncover the truth behind these contentious deportation efforts. His decisions come amidst mounting tensions surrounding judicial independence and the potential ramifications for interbranch relations.