Ambulance Victoria has been convicted and fined $400,000 for failing to keep proper checks on its morphine and fentanyl supplies.
The organisation pleaded guilty to failing to provide a safe working environment and failing to ensure volunteer officers were not exposed to risks.
The outcome follows an investigation into a paramedic who was found dead in 2015, with fentanyl and morphine in his system.
The paramedic was a team manager with 30 years' experience, and the only employee working at the station, when he was found dead at Heywood near Portland. His death was caused by mixed drug toxicity.
Ambulance Victoria was sentenced on Thursday after pleading guilty in Warrnambool Magistrates Court to two breaches of workplace health and safety laws.
It followed a WorkSafe investigation into its management of scheduled medication.
The court was told Ambulance Victoria had exposed the paramedic and volunteer officers at the station to health and safety risks by failing to minimise the potential for illicit access to morphine and fentanyl.
While systems were in place to manage the strong painkillers and these were audited by the team manager, checks on these audits by an area manager weren't done as often as required.
Ambulance Victoria said that since the incident, it had made significant changes to strengthen its management of scheduled drugs.
This included increasing drug security and auditing, a new professional conduct unit and random drug testing throughout the service.
"The thoughts of the staff of Ambulance Victoria remain with the family and friends of our colleague," the organisation said in a statement on Friday.
Australian Associated Press