Two drivers have allegedly tested positive for illicit drugs and a third has been arrested for refusing a test during a police operation at Campbell Town yesterday.
Officers conducted four random drug tests during the two-hour High Street operation, with half returning positive results.
They also carried out 302 random breath tests without detecting a single drink driver.
A 53-year-old Waverley man allegedly refused an oral fluid collection and was arrested at the scene.
He was immediately disqualified from driving for two years and will appear in court at a later date.

Police also detected an unlicensed driver, a suspended driver and an unaccompanied learner driver.
Two vehicles were found displaying false plates. The plates were seized and the drivers were proceeded against.
The Dog Handler Unit allegedly found drugs inside one vehicle. Those drugs were seized and police say a female passenger will be proceeded against.
Transport Safety and Investigation Officers issued 15 defect notices for unroadworthy vehicles.
A Tasmania Police spokesperson said they would keep working with other agencies to make sure vehicles on Tasmanian roads were safe.
“We will also hold to account all drivers who drink or drug drive,” the spokesperson said.
“Even over the winter months, you can expect to see Tasmania Police anywhere, anytime.”