20 CFR 802.214 - Intervention.
(a) If a person or legal entity shows in a written petition to intervene that his, her, or its rights are affected by any proceeding before the Board, the Board may permit that person or legal entity to intervene in the proceeding and to participate within limits prescribed by the Board.
(b) The petition to intervene shall state precisely:
(1) The rights affected, and
(2) The nature of any argument the person or legal entity intends to make.