A Washington Agreement To Join Petition (Joiner) is a document that allows an individual or entity to join an existing petition pending before the United States Supreme Court. It is a way for individuals or entities to become part of the petitioners who are asking the Supreme Court to hear their case. There are two types of Joiner: direct joiner and permissive joiner. Direct joiner is when the petitioner in the original case requests that another person or entity join the petition. Permissive joiner is when the petitioner in the original case does not request any additional parties to join the petition, but the Supreme Court grants permission for another party to join the petition. Both types of Joiner must be approved by the Supreme Court before the additional party is allowed to join the petition.