The Supreme Court of Canada will not hear a union's appeal of a key ruling about random drug testing at Suncor Energy's oilsands operations in northeast Alberta.

Suncor began testing staff in safety-sensitive jobs six years ago, prompting Unifor — which represents some 3,000 workers at the site — to file a grievance claiming the tests infringe privacy.

An arbitration tribunal allowed the union's grievance, concluding the testing policy was an unreasonable exercise of management rights.

However, an Alberta Court of Queen's Bench ruling quashed that decision, sending the matter to a fresh arbitration panel.

Unifor appealed, but the Alberta Court of Appeal dismissed the union's challenge, and Unifor took its case to the Supreme Court.

As usual, the high court gave no reason for refusing to hear the case.