Drivers who get behind the wheel while they are still over the limit from the night before are being targeted in a week-long campaign. Durham Police are setting up checkpoints around the force area, with many being held early in the morning.
They say the summer months are one of the times of the year when drinking and driving increases.
Officers will also be targeting any motorists thought to be under the influence of drugs.
Anyone involved in a road accident or committing a moving traffic offence will be breath-tested.
Time needed
Posters have been sent to pubs across the area urging motorists "don't play games with your licence this summer".
Force casualty reduction officer Pc Dave Nixon said: "A lot of our planned checks will take place early in the morning.
"There are still too many drivers behind the wheel affected by the night or even the day before.
"People do the right thing by catching a taxi home or arranging a lift with a designated driver, only to spoil it by getting in their car at 0700 the next day.
"The only way to get alcohol from your bloodstream is through time, there is nothing you can do to artificially quicken the process."
In 2004, there were 305 drink-related road accidents in County Durham and Darlington with just over half of them resulting in someone being hurt, seriously injured or killed.