The laws around using a phone while driving "could be changed quickly" after the case of a driver who was caught filming a crash.
Ramsey Barreto was found guilty of using his phone to film a crash in north London two years ago.
The 51-year-old then successfully appealed, with his lawyers arguing "he wasn't using it to communicate".
Now two judges at the High Court have criticised the law around driving and mobile phones, which is 16 years old.
"For years we've been arguing that the legislation has become nonsensical," says Emma Patterson, whose law firm took up Mr Barreto's case.
"We've been arguing that unless police can prove beyond reasonable doubt that what someone was doing was actually communicating, it wasn't an offence to be using a smartphone."
How you could be charged
Emma tells Newsbeat that the decision wasn't a loophole, but an example of the law not being used properly.
"The danger of the judgement is people will look at the headline and see the offence of using a mobile phone has changed.
"The judge makes it absolutely clear that you could still be prosecuted for driving without due care or dangerous driving, which carry potentially far higher punishments."
Phones behind the wheel: The law
- Using a hand-held mobile phone or sat nav while driving is illegal
- Any hands-free devices should be fully set up before you drive
- Police still have the power to stop you if they think you have been distracted
- The law still applies if you're stopped in traffic or queuing at lights
- You could get penalty points, a fine and/or a driving ban if you break the law
Source: UK government - read more here
At the hearing the High Court judges agreed that mobile phone laws from 2003 had failed to evolve with the rise of smartphones.
Because it's a top court, Emma thinks it will now put pressure on ministers to change the law.
"We think the law will change very quickly," she says.
"In the meantime it's very likely that police officers that pull you over for fiddling with mobiles are more likely to charge you for driving without due care.