Can rabbis be excommunicated? Is there a hierarchy structure within Orthodox and/or Reform Judaism?
Excommunicated, no, fired yes. Take a Reform Temple. Their beloved Rabbi has retired. They want a new Rabbi. The Union of Reform Temples will look at the size of the congregation and decided how much experience the next Rabbi must have. They send out a Rabbi, and he handles the services and after a few weeks, the Congregation votes to hire him or her or not. (This is usually done by the Temple Board) If hired, that is that. The Rabbi is usually given a one year contract and that get longer as they renew. The contracts contain moral clauses. If they are violated, the Rabbi can be fired. One issue came up with our last Rabbi, he was asked (open forum) if he would perform a marriage service between a Member and a non-Jew. The Rabbi said, no. So, the answer is fired. There is no Hierarchy but there is a honest to G-d employment service. Oh, and all Rabbi are take them or leave them. If you say no, they send you another, but you cannot go back to an earlier rejection.