A motorist tested positive for methyl-amphetamine on 24 October as Casey Highway Patrol officers began Operation Sizzle.
During the operation, 104 breath tests were conducted in conjunction with 113 drug tests in the Casey area.
A total of 20 offenders were caught, with four people driving unregistered vehicles and another who failed to provide registration.
Three defect notices were issued as the high-visibility operation targeted drug-impaired drivers through static testing sites.
Proactive patrols also caught two motorists driving with disqualified licenses, one without their licence and another four with unregistered vehicles.
Two people were fined for not wearing a seatbelt, while one driver failed to display their P-plates.
Another motorist failed to comply with a giveaway sign, and two others were stopped for using a mobile phone and failing to wear a helmet.
A total of three defect notices were issued during the operation, as Casey Highway Patrol looks to conduct similar operations in the future.
