(a) Validity. Validity questions are raised by challenges to a showing of interest on grounds other than adequacy.

(b) Validity challenge. The Regional Director or any party may challenge the validity of a showing of interest.

(c) When and where validity challenges may be filed. Your challenges to the validity of a showing of interest must be in writing and filed with the Regional Director or the Hearing Officer before the hearing opens, unless you show good cause for granting an extension. If no hearing is held, you must file challenges to the validity of a showing of interest before action is taken under §2422.30.

(d) Contents of validity challenges. Your challenges to the validity of a showing of interest must be supported with evidence.

(e) Regional Director investigation and Decision and Order. The Regional Director will conduct an investigation if deemed appropriate. The Regional Director's determination that a showing of interest is valid is final and binding and is not subject to collateral attack or appeal to the Authority. If the Regional Director finds that the showing of interest is not valid, the Regional Director will issue a Decision and Order dismissing the petition or denying the request to intervene.