Devon and Cornwall police are warning New Years revellers not to drive after using a self-testing device to check their alcohol level.
They're concerned that the gadgets can lull people into a false sense of security, making them believe they're safe and legal to drive when they're not.
The head of roads policing Inspector Richard Pryce says the body will continue absorbing alcohol for a while - and drivers could be over the limit by the time they're out on the roads.
Fire destroys two part-built houses on new development
Two derilict buildings destroyed
Devon man to run round mainland Britain
Steve Jones will be first man over 60 to do so, if he makes it
Decision on Exeter swimming pool due this week
Protests gather pace
South Hams tourism down, but average spending up
Sector is worth £266 million to the district
More East Devon council workers leaving
One in eight quit last year
Dartington pool expected to reopen
Developers stumping up £88,000
