Police in Braintree say they have already tried confiscating alcohol, but believe that underage drinkers often manage to hide their drinks.
Officers can now consider breathalysing under-18s they suspect have been drinking. While there is no penalty for a failed test, the youngster will be escorted home by officers and a letter sent to their parents.
Sergeant Tony Benjamin said: "We have been seizing alcohol and are now taking things a step further. It will have a dramatic affect on underage drinking."