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.
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