Clubbers may be required to take a breath test on the door of pubs and clubs in Norwich as part of a trial to increase alcohol awareness.
Thirty venues have been given breathalysers to help revellers gain "better knowledge" of their drinking.
No limit has been set at which to refuse entry as "clubs will be expected to be responsible", police said.
Venues taking part in the month-long trial will record readings to allow the information to be analysed.
The testers will be used by staff at venues, with those taking part bearing the signs "Are you trollied? #DeepBreath".
Insp Ed Brown of Norfolk Police said: "These kits will allow door staff to better gauge how much alcohol someone has had and in turn help them refuse entry to someone who is too drunk.
"This gives additional protection to venues who might otherwise be concerned at the prospect of inadvertently selling alcohol to somebody who is already drunk which is obviously an offence."
Nightclub manager Toby Middleton added: "We want people to enjoy themselves, but we want them to be safe.
"This is one of the tools we've got to give them a better knowledge about their own drinking habits."
Mr Brown added: "All too often we deal with people who are so drunk they cannot think straight and can barely walk.
"They lose all sense of responsibility which clearly makes them vulnerable and that's where the risk increases of someone becoming a victim of crime, being injured or involved in violence and disorder."