Since 2011. An occasional commonplacing of the U.S. Circuit Courts of Appeal.
Not written by a barrister. The name was thought up by a second-year American law student sitting in a coffeehouse in Manhattan. Neither an authoritative statement of the law nor legal advice. Don't rely. Quick work.
Third Circuit: Holly Judge v. Shikellamy School District
Presumptively valid and willful resignation forecloses any direct claim of discriminatory duress. Multi-factor test from 9th governs.