FACA identifies four sources of authority for establishing an advisory committee:
(a) Required by statute.
By law where the Congress establishes an advisory committee, or specifically directs the President or an agency to establish it (non-discretionary );
(b) Presidential authority.
By Executive order of the President or other Presidential directive (non-discretionary );
(c) Authorized by statute.
By law where the Congress authorizes, but does not direct the President or an agency to establish it (discretionary ); or
(d) Agency authority.
By an agency under general authority in title 5 of the United States Code or under other general agency-authorizing statutes (discretionary ).