In a court case that could very well define the limits of Donald Trump’s presidential power, a federal judge Thursday reinstated a member of a federal labor agency, warning of the damage to the country if Trump continues to rule as if he were a king.

U.S District Judge Beryl Howell reinstated Gwynne Wilcox to the National Labor Relations Board after Trump removed her without providing any cause, issuing an opinion that suggests the case could be a broader test of the “unitary executive theory.”

“An American President is not a king — not even an ‘elected’ one — and his power to remove federal officers and honest civil servants like plaintiff is not absolute,” Howell wrote.

Wilcox brought her case last month to challenge her late-night firing from the National Labor Relations Board and she seemingly acknowledged that her lawsuit — following a “string of openly illegal firings” — might become a “test case” for the limits of presidential power. Howell’s 36-page ruling seemingly took the cue, offering a broad criticism that Trump’s interpretation of his scope of power flatly violates the Constitution and risks lasting damage to the country.

“The President’s interpretation of the scope of his constitutional power — or, more aptly, his aspiration — is flat wrong,” Howell wrote.

Citing the White House’s Feb. 19 “Long Live the King” post of Trump wearing a crown, Howell suggested that the president is attempting to govern like a monarch.

“A President who touts an image of himself as a ‘king’ or a ‘dictator,’ perhaps as his vision of effective leadership, fundamentally misapprehends the role under Article II of the U.S. Constitution,” she wrote.

Rather than being a “conscientious custodian of the law,” Trump has been testing the limits of his power before courts stop him, according to Howell.

“The President seems intent on pushing the bounds of his office and exercising his power in a manner violative of clear statutory law to test how much the courts will accept the notion of a presidency that is supreme,” Judge Howell wrote.

Notably, Howell’s decision invoked the “unitary executive” — a theory that the president can exercise complete control over the executive branch — and suggested the case could become a way to materialize what has long been an “academic exercise” about the president’s power into law.

“To start, the Framers made clear that no one in our system of government was meant to be king — the President included — and not just in name only,” she wrote.