Car insurance firms can breathe a sigh of relief after more than 600 drivers were breath-tested without a single one being over the limit.
In an ongoing safety campaign, Durham Police tested 602 motorists across the county to detect drink or drugs in their system.
They carried out the voluntary testing in the morning, in a bid to catch out people who were over the limit from the night before.
All results came back negative, a result which the force described as "heartening" and a good result for road safety.
Acting Chief Inspector Ken Cook, of the force's strategic road policing department, said: "This was a concerted effort by our staff to ensure that motorists are abiding by the legislation.
"The overall aim is to reduce the number of casualties on our roads and I am heartened by the fact that every single one of the tests carried out was negative."
© Press Association 2010