A French court has ruled that a citizen cannot smile in passport photos, saying that the variation of a smile's length can confuse face recognition software.The decision follows an attempt by an unnamed official who appealed to the court after his own passport photo was rejected for breaking stringent rules.A February 2009 decree designed to ensure that passport photographs meet ICAO specifications, state that a person's look and expression must be “fixed on the lens. The expression should be neutral with the mouth closed”.Known as “Thierry”, the claimant claimed that he was not smiling on the incriminated pictures, but instead had a neutral face with the corners of his mouth turned up.