The free press guaranteed by our Constitution is encountering a new — and growing obstacle: a flat refusal by many public officials to divulge what is going on in their conduct of office. JAMES S. POPE,Managing Editor of the Louisiille Courier-Journal for the past eleven years, is a director of the American Society of Newspaper Editors and chairman of that group’s Committee on Freedom of Information. He is also a director of the Associated Press Managing Editors.