How easy should it be to fire bad public school teachers? That’s what’s being reconsidered in an appeals court today in the landmark case Vergara v. California. In 2014, a judge sided with the students who brought the case. He found that the tenure system in California violates students civil rights, because the worst teachers are sent to the highest poverty schools, meaning those students get an unequal education. The state and two unions that joined the case appealed. Today, a court is hearing their arguments. If the decision is upheld, it would be a major blow to teachers unions in California and in the rest of the country.