Police have this week launched a campaign called Operation Holly to catch drink and drug drivers in Milton Keynes as we count down to Christmas.
And they are urging people to shop anybody they see about to take the wheel while under the influence.
The move is a bid to reduce the amount of drug and alcohol-related traffic collisions on MK roads over the festive season.
Throughout this week and every week up until January 1, officers will be stopping motorists to carry out breath tests, drug tests and special field impairment tests.
Impairment tests can involve checking the size of the driver's pupils, which some drugs can cause to shrink or enlarge, and asking them to stand on one leg without swaying.
The test can also involve asking the suspect to walk in a straight line or tilt their head back with their eyes closed in order to check the ability to balance. They may be asked to touch their finger to their nose to check coordination.
If anyone fails the test, a police officer can arrest them on suspicion of driving while impaired. and they will be taken to a police station to give ea urine, blood or saliva sample.
On average 20 per cent of all fatal collisions involve an impairment from drink or drugs, and In the Hampshire and Thames Valley force area, around 400 drink drivers are caught a month.
Sergeant Scott Kerr, Road Safety Sergeant for Hampshire and Thames Valley Police said: “Every year officers deal with cases of drink or drug driving that directly result in families facing Christmas without loved ones. Even the smallest amount of alcohol or drugs in your system can affect your ability to drive safely.
He added: “Friends, colleagues and family members can positively influence those around them. So we are calling on them to stop potential drink or drug drivers from getting behind the wheel and risking tragedy this Christmas.
“We’ll be running targeted operations across the region to enforce the law on drink and drug driving: you can face a fine of up to £5000, disqualification from driving, and a lengthy prison sentence. If you know someone who drink or drug drives you can help by reporting them on 101 or call 999 if they are driving or immediately about to drive under the influence.
Sgt Kerr is urging people to plan ahead during the festive season, to think about how they are going to get home, and not to forget about the impact alcohol and drugs can still have the morning after.
He said: “Our message is simple: Don’t drink or drug drive – It’s not worth the risk.”
Police are encouraging the public to report drink and drug drivers with as much information and detail as possible so they can be targeted.
If you know someone who drink or drug drives you can report them online or by calling 101. if you wish to remain anonymous, you can contact Crimestoppers on 0800 555 111.
But if there is an immediate risk to the public always call 999, say police.