The following is taken from a rather influential source of US law:

Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.

Now, where in this amendment does it say that ANYONE is free to simply say any thing? Or that a prayer CAN'T be said? "CONGRESS SHALL MAKE NO LAW..." is misunderstood to mean that any local jurisdictional body is the equivalent of the US Congress AND that saying a prayer is the same as passing a law. There have been idiots in the Judiciary Branch of our government. Unfortunately the precedents they set are still in place.