“The same applies to any other use of the phone while driving.”
The penalty for driving while using a hand-held mobile phone is six points on an offender’s licence and a fine, up to a maximum of £1,000.
Mr Barreto was seen by a police officer holding his phone up to his car window for 10 to 15 seconds as he drove past the scene of a serious accident in August 2017.
Mr Barreto was convicted in July last year, after a magistrates’ court trial, of driving while using a hand-held mobile phone – under the terms of the Road Traffic Act and the Road Vehicles Regulations.
But after his conviction was overturned on appeal at Isleworth Crown Court in October last year, the Director of Public Prosecutions (DPP) launched a legal challenge.
At a hearing in London in April DPP lawyers argued that the legislation prohibits all phone use while driving.
However, the Crown Court’s decision was upheld.
Mr Barreto’s lawyers said the law had “failed to keep pace” with technological advances in smartphones.
Francis Noakes, of the Get Licensed Driving School, said the case showed prosecutions are “far from straightforward”.
He added: “When it comes to road safety, we simply can’t allow for any uncertainty to exist.