The Watchtower Society teaches that Witnesses must give just as much faith, confidence, and compliance to the teachings of the "Slave Class" (in reality; the Governing Body) as they would the inspired writings of the apostles.
Yet, when errors are admitted and doctrinal changes are made, the friends are reminded that the "Faithful Slave" is not inspired and is not infallible.
Excellent way to put it. It's a double standard that all the cults have.