After clerking, he entered private practice as an associate at the Boston law firm of Foley, Hoag & Eliot, where he worked on labor and employment cases and other commercial disputes.

[4] On June 26, 2017, Kafker was nominated by Governor Charlie Baker to replace retiring Justice Geraldine Hines on the Supreme Judicial Court.

[6] The agreements called for clean electricity generated in Canada to be transmitted to Massachusetts via a transmission line running from Québec to Maine.

Kafker explained that the instructor did not meet the definition of a "minister," in part because she was never ordained and never received formal religious training, and so the ministerial exception did not bar her lawsuit.

[11][12] The United States Supreme Court declined a request to review the decision, though four justices (Samuel Alito, Clarence Thomas, Brett Kavanaugh, and Amy Coney Barrett) expressed an interest in revisiting the scope of the ministerial exception in a future case.