Scores of pub-goers in Bicester were tested for traces of illegal drugs during a police operation aimed at tackling violent street crime.
Police used the force's new drugs itemiser - which scans people for traces of banned substances - at the Litten Tree pub.
It was the first time the new technology, which detects traces of drugs from heroin to cannabis, had been used in the town.
Police officers tested 150 revellers as they arrived at the pub in Sheep Street between 10.30pm and midnight on Friday.
The pub managers barred anyone refusing to co-operate with the test from entering.
Det Sgt Steve Duffy, of Banbury CID, said two people tested positive and were searched but not found to be in possession of drugs.
The pair were then banned from entering the pub, but not arrested.
Mr Duffy said: "It went very well. We gained the full co-operation of the management and the customers.
"Everyone was very supportive and compliant.
"We swab people's hands and then that swab is placed into the equipment and it gives a reading of the level of drug residue.
"If it's above the background level then we use the equipment to give us the power to search - it gives us reasonable suspicion."
Mr Duffy explained the machine also picked up tiny traces of drugs that innocent people could get from handling contaminated bank notes.
But he said officers only searched those showing a more substantial level of drug residue.
He said: "The public were very supportive. Many people were saying they wanted to be tested.
"Bicester has no bigger problem than the rest of the country but we are never complacent.
"It gives us an indication of drug activity and where it's taking place. It is part of a wider initiative to reduce violent crime.
"We associate binge drinking and illegal substances as being one of the causes of spontaneous unprovoked street crime."
The drug itemiser was also used in Witney and Banbury two weeks ago. About 260 revellers were tested, with one person arrested on suspicion of possessing class A and C drugs. Two others also tested positive.