Two important questions that agencies must answer in adjudications is who must be given notice and who may participate in adjudications. There are a number of ways one can participate in an administrative proceeding. Obviously, if one is a named party, participation is required. Many APA provisions refer to parties in interest. In addition, a person who qualifies as a party in interest may seek intervention.

That is, if a person is not a named party in an administrative proceeding or lawsuit but is a party in interest, he or she may become part of the proceeding. Thus, it must be determined who qualifies to be a party in interest. The APA does not expressly define the phrase party in interest. However, the courts have provided some guidance in this area.

First, there are obvious parties who must be allowed to participate. Those who are the subject of an agency action must be provided with notice and given an opportunity to participate in all hearings. The line between those who are parties in interest and those who are not is not always easy to draw. Generally, the law of party in interest parallels the law of constitutional standing. That is, if an individual satisfies the standing requirements for participating in a judicial proceeding, the individual is a party in interest at the administrative level.