Unions will take a major blow in the upcoming Janus vs. AFSCME case if the Supreme Court rules that agency fees are unconstitutional. Agency fees, which some states require non-union employees to pay unions for representation, have been a lynchpin of union membership. Take the NEA – America’s largest teachers union. The 22 states with agency fees are home to 69% of NEA members. Agency fees are pivotal because they change the cost of union membership. Take California: Teachers can pay a thousand dollars to join the union, or not join but still pay six hundred and fifty dollars in agency fees. With no fees, teachers choose to pay a thousand dollars or zero. As the cost of joining soars, union membership will fall. No one knows by how much, but since 2010, three states dropped agency fees and in them, the NEA shrank between 17% and 59%. A defeat in Janus will weaken America’s most powerful education interest groups. The long-term question is, “By how much?” For more on Janus, agency fees, and why they are so important for teachers union membership, check the links in the description below. Also, let us know what other topics you’d like our scholars to cover in 60 seconds. And be sure to like and subscribe for more research and videos from AEI.