Judiciary Committee Chairman Jerry Nadler said Hicks’ blanket refusal to tell lawmakers about her tenure in the West Wing is the real-life illustration Democrats needed to show a judge just how extreme the White House’s blockade on witness testimony has become.

“It very much played into our hands,” Nadler said in an interview in his Capitol Hill office Thursday. “It’s one thing to tell a judge blanket immunity is not a right thing. It’s another thing when a judge can see what that means in actuality, and how absurd it is.”

Nadler said he is working with the House general counsel to draft the lawsuit against McGahn, a central witness for special counsel Robert Mueller. The New York Democrat said he’s confident that a win in the McGahn case would create a precedent that forces the White House to back off its resistance to Democrats’ investigations and permit other key Mueller witnesses, like Hicks, to talk to lawmakers.