A faculty is a legal instrument or warrant in canon law, usually an authorisation to do something.
In the canon law of the Catholic Church, a faculty is "the authority, privilege, or permission, to perform an act or function.
In a broad sense, a faculty is a certain power, whether based on one's own right, or received as a favour from another, of validly or lawfully doing some action".
[1] In the Church of England (whose canons have the status of national law) the "faculty jurisdiction" is set out in the Care of Churches and Ecclesiastical Jurisdiction Measure 1991, and the Faculty Jurisdiction Rules 2015.
The parish has to prepare a petition for the faculty and the chancellor of the diocese may grant the faculty after due consideration.