A big jump in the proportion of people caught in the festive drink driving campaign is down to smarter testing, Derbyshire police have said.
In December, officers stopped 1,011 people and 121 - 11% - tested positive or refused to provide a sample.
This compares to last year which saw a positive test rate of 4% from more than 4,500 motorists stopped.
Police said they had targeted persistent drink drivers or acted on specific information.
Chf Insp Tim Frohwein, head of Roads Policing for Derbyshire Constabulary, said while it was disappointing some people still got behind the wheel after drinking, he was pleased with their new approach.
He added: "People who suspected others of getting behind the wheel after a drink called the police to tell us and 21 calls about drink-drivers were made to Crimestoppers. We are grateful to these callers for their assistance.
"Although fewer tests were administered, the percentage of positive tests was far higher than in previous years, proving the value of our intelligence-led approach in 2009."
The crackdown was backed up by an educational programme which saw posters and leaflets handed out in pubs and clubs.