The B.C. Supreme Court ordered the province's Workers' Compensation Appeal Tribunal to reconsider the case after concluding the tribunal's decision failed to properly weight evidence about whether the teachers were poisoned.
The case involves Ivan McKnight, Hugh MacPherson, Lynne Williams, Russell Reid, David Hill and David Martin, who were all teachers at Mount Baker Secondary School in Cranbrook, B.C.
The teachers each applied for workers' compensation benefits in 2004 and 2005, claiming exposure to mercury in the school had made them ill with symptoms that included anxiety, irritability and depression.
The Workers' Compensation Board rejected their claims, as did the appeal tribunal in 2010.
While the appeal tribunal heard evidence the teachers were exposed to mercury, which several doctors testified could have caused the teachers' symptoms, the appeal panel concluded the evidence wasn't sufficient to prove they were poisoned.
But B.C. Supreme Court Judge Anthony Saunders said the appeal tribunal placed an unfair burden on the teachers, essentially requiring them to demonstrate a medical diagnosis of mercury poisoning, even though the provincial law that governs such claims does not require that level of proof.
"The panel’s finding of the insufficiency of evidence in support of there having been mercury poisoning ... was a breach of WCB policy, and a breach of the panel’s obligation under (the Workers Compensation Act)," Saunders wrote in a decision posted to the court's website on Wednesday.
"The petitioners have succeeded in demonstrating that the panel was patently unreasonable in failing to weigh all of the relevant evidence, and in imposing a requirement that mercury poisoning be proven as that diagnosis would be made by physicians."
The Appeal Tribunal heard evidence of mercury exposure at the school.
In 1954, between 100 and 150 millilitres of mercury spilled at the school, though not all of it was recovered. There had been science classes in which mercury was passed around. Broken thermometers were "frequent" and there were "significant spills" from mercury barometers in 2001 and 2004, according to the B.C. Supreme Court decision.
Mercury assessments were conducted at the school in 2005 and remediation was undertaken shortly afterwards.
Evidence from doctors at the tribunal differed on whether the teachers had been exposed to unsafe levels of mercury or whether that was the definitive cause of their symptoms.
However, Saunders wrote in his decision that there was indeed evidence that the teachers were poisoned and he chided the tribunal for not properly explaining why it favoured some pieces of evidence and dismissed others.
In one passage of the tribunal's decision, Saunders noted, the appeal panel appeared to be concerned that other explanations for the workers' symptoms had not been ruled out, even though it did not specify just what those alternative explanations could be.
"The panel's finding of deficiencies in the claimants' case based on their failure to account for evidence that was not before the panel, effectively put the claimants to a considerable, if not impossible, burden," he wrote.
The B.C. Supreme Court judgment did not make any findings about whether the teachers were, in fact, exposed to unsafe levels of mercury or whether they had suffered mercury poisoning. Instead, Saunders ordered the tribunal to tackle the case again — this time weighing the evidence properly.
The B.C. Teachers' Federation issued a news release welcoming the ruling.
"All school staff and students deserve to have safe environments for teaching and learning," federation president Susan Lambert said.
"It’s a terrible shame it has taken so long for these teachers to get a fair consideration of the evidence, especially considering the devastating impacts on their health, careers, and lives."