“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,” Judge Ketanji Brown Jackson wrote.

“Stated simply, the primary takeaway from the past 250 years of recorded American history is that Presidents are not kings,” Jackson said.

…The ruling stops short of saying White House officials must answer all questions they’re asked before Congress. Instead, the ruling focuses on whether an official like McGahn must appear for testimony once subpoenaed.

Federal judge says former White House counsel Don McGahn must speak to House – CNNPolitics

hmmm