The 2017–18 Supreme Court term was noteworthy for many reasons. One is the fact that the Court overruled two longstanding (at least 40 years old) constitutional precedents by 5–4 votes, albeit with different lineups. In Janus v. American Federation of State, County and Municipal Employees, Council 31, the five more conservative justices held that it violates the First Amendment for public employees who choose not to become a member of the public sector union that represents them to nonetheless have to pay so-called “fair share” fees to the union to defray the cost of collective bargaining. In contrast, in South Dakota v. Wayfair, Justice Ginsburg joined four of the more conservative justices in the majority to uphold against a Commerce Clause challenge a state law requiring an online retailer that does significant business in the state but that lacks a brick-and-mortar presence in the state to collect and remit sales taxes, while the usually more conservative Chief Justice Roberts led Justices Breyer, Kagan and Sotomayor in dissent.
Notwithstanding these distinctive lineups (which perhaps can be explained at least in part by reference to the subject matter of the two cases) the justices’ writings in both cases, looked at in connection with each other, can help us better understand important principles about the proper way to implement the doctrine of horizontal stare decisis—the Court’s respect its own prior rulings. In particular, I focus below on the justices’ approach to three questions that are raised by one or both of the high-profile stare decisis cases of last term…..