Houses of worship have every right to preach on social issues and to take part in advocacy campaigns. Politicians cannot - no matter where you stand on the central issue involved in this case, LGBT-rights - subpoena sermons from clergy. This is a clear effort by a progressive politician to intimidate conservative clergy. It cannot be allowed, as the Interfaith Alliance has rightfully said. What if an anti-gay mayor demanded by court order to see copies of sermons given by United Church of Christ clergy on behalf of marriage equality? This reprehensible effort by Houston Mayor Annise Parker must be halted to protect the religious freedom of all. I fully support the Houston Equal Rights Ordinance (HERO) as an important civil rights victory. In defense of HERO, however, Mayor Parker has crossed a line no politician in America should cross.