Sanctuary, referring to the right of a supplicant to seek refuge or safety in a church, was actually a component of medieval European law. In pre-Reformation England there were actually stone seats in some churches (know as "frithstools") for those who wished to seek sanctuary—or, more commonly, large door knockers or rings that the seeker of asylum could hold to be assured of protection. By the end of the eighteenth century the right of sanctuary was no longer upheld in Europe.
In the 1980s and 90s in the US various denominations joined together to protect Central American refugees from the Immigration and Naturalization Services by offering sanctuary in their churches and houses of worship. This original Sanctuary Movement has been revived as the New Sanctuary Movement, and continues to work to protect immigrant families.