Perich complained to the federal Equal Employment Opportunity Commission, which sued the church for violations of the disabilities act.
A federal judge threw out the lawsuit on grounds that Perich fell under the ADA's ministerial exception, which keeps the government from interfering with church affairs. But the 6th U.S. Circuit Court of Appeals reinstated her lawsuit, saying Perich's "primary function was teaching secular subjects" so the ministerial exception didn't apply.
The 6th circuit's reasoning was wrong, Roberts said. He said that Perich had been ordained as a minister and the lower court put too much weight on the fact that regular teachers also performed the same religious duties as she did.
The circuit court also placed too much emphasis on the fact that Perich's religious duties only took up 45 minutes of her workday, while secular duties consumed the rest, Roberts said.
"The issue before us ... is not one that can be resolved by a stopwatch," he said.
But since this was the first time the high court has ever considered the "ministerial exception," it would not set hard and fast rules on who can be considered a religious employee of a religious organization, Roberts said.
"We are reluctant ... to adopt a rigid formula for deciding when an employee qualifies as a minister," he said. "It is enough for us to conclude, in this, our first case involving the ministerial exception, that the exception covers Perich, given all the circumstances of her employment."
The court also refused to extend the ministerial exception to other types of lawsuits that religious employees might bring against their employers, like breach of contract lawsuits.
Justice Clarence Thomas wrote in a concurring opinion that in future cases, he thinks the lower courts should defer to the religious organization on who it thinks "qualifies as its minister" instead of letting a judge decide.
"A religious organization's right to choose its ministers would be hollow ... if secular courts could second-guess the organization's sincere determination that a given employee is a 'minister,'" Thomas said.
Justice Samuel Alito, who wrote a separate opinion, argued that the exception should be tailored for only an employee "who leads a religious organization, conducts worship services or important religious ceremonies or rituals or serves as a messenger or teacher of its faith."
But "while a purely secular teacher would not qualify for the 'ministerial exception,' the constitutional protection of religious teachers is not somehow diminished when they take on secular functions in addition to their religious ones," Alito said.