Idaho Admin. Code r. 62.01.01.705
If a petition to intervene shows direct and substantial interest in any part of the subject matter of a proceeding, does not unduly broaden the issues, and does not unduly delay or prejudice the original parties, the presiding officer will grant intervention, unless the petitioner's interest is already adequately represented by one or more parties already participating in the case. The order granting intervention may be subject to reasonable conditions as determined by the presiding officer, including limiting the factual or legal issues the intervenor may raise and/or the means an intervenor may use to present and develop those issues, so as to avoid undue delay or prejudice to the original parties. If it otherwise appears that an intervenor has no direct or substantial interest in the proceeding, or that intervention would unduly broaden the issues, or unduly delay or prejudice the original parties, the presiding officer may deny the petition.
Idaho Admin. Code r. 62.01.01.705