A federal judge ruled Monday that President Trump does not have the power to block former White House Counsel Don McGahn from showing up for compelled testimony in front of Congress.

In a 120-page opinion, U.S. District Judge Ketanji Brown Jackson of Washington ruled: “Executive branch officials are not absolutely immune from compulsory congressional process — no matter how many times the Executive branch has asserted as much over the years — even if the President expressly directs such officials’ non-compliance.”

The judge said that “no one is above the law.”

“That is to say, however busy or essential a presidential aide might be, and whatever their proximity to sensitive domestic and national-security projects, the President does not have the power to excuse him or her from taking an action that the law requires,” she said.

Jackson’s decision is a boost for Democrats as they move forward with their impeachment inquiry into President Trump. Democrats are expected to address the Trump administration’s obstruction of their investigation in their impeachment articles, and the Trump administration immunity claim that the judge dismantled in the McGahn case is the same justification the White House has invoked in directing witnesses in the Ukraine matter not to testify to Congress.

Additionally, the House has told the judge that it could seek McGahn’s testimony as part of the impeachment proceedings.

In her opinion, Jackson said that the Justice Department had it “exactly backwards” by claiming, in her words, that “Presidents can lawfully prevent their senior-level aides from responding to compelled congressional process and that neither the federal courts nor Congress has the power to do anything about it.”

Quoting a similar case from the George W. Bush administration, the judge said that McGahn “must appear before the Committee to provide testimony, and invoke executive privilege where appropriate.”

A Justice Department spokesperson told TPM the administration will appeal the decision.

The House brought the lawsuit against McGahn in August, months after Democrats subpoenaed him for his testimony about episodes detailed in special counsel Robert Mueller’s report.

In the case, the Justice Department asserted that McGahn, as a former top advisor to Trump, was shielded from testimony by an “absolute” immunity, and said that, because of the immunity, Congress could not even compel McGahn to show up to his scheduled deposition.

The judge had harsh words for the administration’s legal logic, at one point comparing it to the line from George Orwell’s “Animal Farm” that “All animals are equal but some animals are more equal than others.”

The judge said the Justice Department’s legal arguments “transgress core constitutional truths (notwithstanding OLC’s persistent heralding of these and similar propositions).”

Citing “textbook constitutional law,” she pointed to the judicial branch’s power to power “to demarcate the boundaries of lawful conduct by government officials” and Congress’ power to “investigate potential abuses of official authority.”

“What is missing from the Constitution’s framework as the Framers envisioned it is the President’s purported power to kneecap House investigations of Executive branch operations by demanding that his senior-level aides breach their legal duty to respond to compelled congressional process,” she wrote.

Jackson is the latest judge to rule against the administration in its efforts to evade congressional oversight. Courts have previously backed a congressional subpoena of Trump’s accounting firm for his financial records in a case that is now in front of the Supreme Court. An appeals court, meanwhile, is reviewing a lower court decision permitting the disclosure of certain grand jury materials from Mueller’s investigation to the House.

Read the opinion below: