As New York’s Rockland County grapples with a large and lengthy outbreak of measles, a group of anti-vaccine parents sued officials for temporarily barring their unvaccinated children from school—and the county is not having it.

In a fiery response, Rockland County Attorney Thomas Humbach forcefully defended the legality of the county’s move, which was intended to thwart the spread of disease. He also went so far as to cast doubt on the validity of the religious exemptions the parents had used to opt their children out of required vaccinations.