Also known as: mass joinders · joinder
Written by attorneys · grounded in primary & secondary sources — see below
A procedural device permitting numerous individual plaintiffs or defendants to assert or defend claims together in a single action when class certification is unavailable or impracticable.
Melanie Morris and 247 other homeowners sued Midwest Airlines after repeated low-altitude flights damaged their roofs. The court denied class certification because individualized damage calculations predominated. The plaintiffs therefore proceeded by mass joinder, filing a single complaint that named every homeowner as a party.
Marco Marquez sued Meridian Motors in federal court for breach of a supply contract. After discovery revealed related warranty claims held by 38 other dealers, Marco joined them as additional plaintiffs. The court exercised supplemental jurisdiction over the new claims because they arose from the same nucleus of operative facts.
Select any source to read its text and confirm it supports the definition.
Michael Miller conveyed real property to Majestic Construction without first obtaining his wife Maria Morales's written consent. After Michael died, the probate court required Maria to join the proceeding so her elective-share rights could be adjudicated alongside the other heirs.
Miles Montgomery and Maxwell Manufacturing litigated title to equipment located in State B. The State A court applied its own procedural rules to the joinder of additional lienholders while using State B substantive law to decide ownership.
Megan Moore, an escrow agent, faced conflicting demands from 19 investors over a single fund. She filed an interpleader action naming all claimants as defendants so the court could determine the proper distribution in one proceeding.
A foreign supplier was added as a defendant in an action already pending against two domestic manufacturers. The court disregarded the foreign defendant's citizenship when determining proper venue for the remaining parties.
Mass joinder is used when the requirements for class certification cannot be satisfied, such as when individualized issues predominate or numerosity makes joinder impracticable under Rule 23(a)(1). Plaintiffs then proceed by naming each party individually in a single complaint.
Supporting sources
Yes. Under 28 U.S.C. § 1367(a), once a district court has original jurisdiction, it may exercise supplemental jurisdiction over claims involving the joinder of additional parties that form part of the same case or controversy.
The joinder of a defendant not resident in the United States is disregarded when determining venue for the remaining defendants under 28 U.S.C. § 1391(c)(3).
…under Article III of the United States Constitution. Such supplemental jurisdiction shall include claims that involve the joinder or intervention of additional parties.” The statute’s grant of supplemental jurisdiction is broad. It applies to “all other claims” that form part of the same “case or controversy” as a…