5 CFR 2422.9 - How is the adequacy of a showing of interest determined?
(b)Regional Director investigation of showing of interest and Decision and Order. The Regional Director will conduct an investigation if deemed appropriate. A Regional Director's determination that the showing of interest is adequate is final and binding and not subject to collateral attack at a representation hearing or on appeal to the Authority. If the Regional Director determines that a showing of interest is inadequate, the Regional Director will issue a Decision and Order dismissing the petition, or denying a request for intervention.