a. Intervention. When a person has an interest in the subject matter of a lawsuit between other parties and that interest might be affected by a decision in the lawsuit, or a person has a claim or defense in common with a claim or defense in a lawsuit between other people, the person may be able to participate in the lawsuit as a plaintiff or as a defendant. Joining a lawsuit in this way is called “intervention.” Procedures for intervention are provided in Rule 24 of the Arizona Rules of Civil Procedure, which is included in the appendix to these Rules. [ARCP 24]

b. Interpleader. When a person might be exposed to double or multiple liability because of claims made against that person, the person may file a lawsuit against those who have the claims, and the court will determine each party's rights and liabilities. For example, a person who has property in which two or more other persons claim ownership may file a lawsuit asking the court to determine ownership. This type of action is called an “interpleader.” Procedures for interpleader are provided in Rule 22 of the Arizona Rules of Civil Procedure, which is included in the appendix to these Rules. [ARCP 22]