Oilsands giant Suncor Energy will make arguments before the Alberta Court of Appeal on Wednesday against an injunction that prevents the company from testing its employees for drugs and alcohol.
Suncor announced in June that it would start the random tests on Oct. 15, 2012.
But that was halted on Oct. 12 after Alberta Court of Queen's Bench Justice Eric Macklin granted a temporary injunction that was requested by the Communciations, Energy and Paperworkers over concerns about worker privacy.
The judge ordered that a labour arbitration board must first rule on a union grievance about the policy before it can go ahead.
Suncor is asking that the injunction be overturned so the testing program can go ahead.
The company says that there have been three deaths at its plant since 2000 related to drug and alcohol use.