summary: religious freedom shall not be limited except when a government can prove a "compelling interest" to do so. And then, the government must select a method that results in the least possible interference with religious freedoms of individuals, churches and other organizations. This is a very onerous burden on the government, and applies to every law that is passed.
This law had a major influence in over 90 court decisions since it was enacted late in 1993.
An interesting case (City of Boerne v. Flores, No. 95-2074) arose in 1996. It involved the Roman Catholic Archbishop of San Antonio, TX. The city of Boerne TX refused to issue a construction permit which would have allowed the church to expand into a historical district. The expansion was needed because of an increase in the size of the congregation. The church sued under the RFRA; the federal judge determined that the act was unconstitutional. It has since been reviewed by several appeals courts who have ruled the act constitutional. In mid October, 1996, the Supreme Court of the US agreed to rule on the case. They issued their ruling on 1997-JUN-25, declaring the law to be unconstitutional. The vote was 6 to 3.
Congress will now consider a new RFRA bill that might guarantee religious rights while staying within constitutional boundaries. Senator Edward Kennedy (D, MA), "We cannot take this 'no' from the Supreme Court as the final answer." In the meantime, several states have passed a law very similar to the original RFRA; these may well be unconstitutional.