State bar ethics committees, facing numerous requests for guidance from lawyers, increasingly are examining the ghostly footprints of electronic metadata — often with widely varying results.

“When I first gave a lecture on metadata four years ago, there was only the New York ethics opinion,” recalled legal ethics scholar Andrew M. Perlman of Suffolk University Law School. “In the last year, there has been four or five more. In the next three to four years, I expect we will see an explosion of opinions. This is just beginning.”