What does impasse mean? Impasse is essentially a deadlock between the negotiating parties.  In this case, CHSTA and CUHSD jointly filed a request with the Public Employee Relations Board (PERB) for a determination of impasse. On May 26, PERB determined the existence of an impasse and referred the case to the State Mediation and Conciliation Service for the assignment of a mediator. If a mediator is unable to effect a settlement, they may certify the dispute to fact-finding for resolution. 

(Source: California Public Relations Board)