Oilsands giant Suncor will have to wait until next week to find out whether it will be able to start conducting random drug and alcohol tests on its northeastern Alberta employees.

A union representing 3,000 workers is seeking an injunction to prevent the company from proceeding with the tests, which the company planned to implement on Friday.

After hearing extensive arguments from both sides in an Edmonton court room on Thursday, Justice Paul Belzil told both parties he will deliver a written decision next Thursday.

It's the latest development between Suncor and Unifor 707A, which have been fighting over the issue since 2012, when Suncor introduced the tests for workers in the most safety-sensitive jobs.

"I believe the judge was very, very well-versed in this case," said Ken Smith, president of Unifor 707A. "He definitely had given it a lot of thought and we feel optimistic."

Suncor declined to comment until after the decision.

Back-and-forth battle continues

But Suncor is the most recent victor in the ongoing battle.

In the spring of 2016, Justice Blair Nixon overturned arbitration that favoured the union's position that the random testing would violate workers' privacy.

Nixon said the panel should have considered data on union and non-union employees to understand the impact of drugs and alcohol in the workplace.

In the fall of 2017, the Alberta Court of Appeal dismissed the union's challenge of Nixon's decision.The union is now seeking leave to challenge the Alberta Court of Appeal ruling at the Supreme Court.

Privacy versus safety

On Thursday, the union's lawyer, John Carpenter, made the familiar argument that random drug and alcohol tests violate privacy, dignity and bodily integrity.

He cited the negative experiences of a number of employees who have been subjected to the reasonable cause tests — performed when supervisors have evidence to suspect a worker of using drugs — the company has long conducted.

Suncor's lawyer, Barbara Johnston, reiterated evidence of substance abuse in the workplace. She cited cases in which employees were put in danger as a result of drug and alcohol use.

Belzil emphasized on multiple occasions throughout the day-long hearing that his decision will only be with respect to putting a temporary injunction on the tests.

roberta.bell@cbc.ca

@roberta__bell