Executive privilege may block certain materials from discovery in a criminal campaign-finance case against two associates of Rudy Giuliani, said the lawyer for one of the two defendants at an arraignment in the U.S. District Court for the Southern District of New York on Wednesday.

Lev Parnas and Igor Fruman, two foreign-born associates of Giuliani who have been indicted in a scheme to violate U.S. campaign-finance laws, pleaded not guilty to charges of conspiracy and falsifying records in Manhattan federal court.