In the various challenges to Trump's two travel bans, the challengers cited and the courts referenced Giuliani's TV interview in which he disclosed that Trump had asked him to fashion a travel ban that would achieve Trump's goals legally. Specifically, the Washington Post reported Giuliani's comments on Fox quoted below. Did Giuliani disclose confidential information? Maybe he had express or implied permission if so. It might have seemed that the disclosure would help Trump, though it has made the bans appear to be a subterfuge.
From the Post:
“I'll tell you the whole history of it,” Giuliani responded eagerly [to a question in a Fox interview]. “So when [Trump] first announced it, he said, 'Muslim ban.' He called me up. He said, 'Put a commission together. Show me the right way to do it legally.' "
Giuliani said he assembled a “whole group of other very expert lawyers on this,” including former U.S. attorney general Michael Mukasey, Rep. Mike McCaul (R-Tex.) and Rep. Peter T. King (R-N.Y.).
“And what we did was, we focused on, instead of religion, danger — the areas of the world that create danger for us,” Giuliani told Pirro. “Which is a factual basis, not a religious basis. Perfectly legal, perfectly sensible. And that's what the ban is based on. It's not based on religion. It's based on places where there are substantial evidence that people are sending terrorists into our country.”