Rule 18.Joinder of claims
Group IV: Parties · Last amended March 1, 2019 · Last verified July 14, 2026
Full Text of Rule 18
Notes
Drafter’s Note, Amendment Effective January 1, 2005: The amendments are technical.
Amendment History
Amended eff. 9-27-71; Amended eff. 1-1-05; Amended eff. 3-1-19.
Plain-English Summary
Once two sides are already in court against each other, Rule 18 removes any limit on how many separate legal theories or demands one side can throw into the same case. A plaintiff suing over a car accident, for instance, is not stuck filing separate lawsuits for the property damage and the medical bills; both can ride together in one complaint, along with any other unrelated claim against that same defendant. The same freedom applies to counterclaims, crossclaims, and claims against a third party brought into the case.
The rule also lets a party join a claim that only becomes relevant depending on how another claim turns out, without waiting for the first claim to be resolved. The classic example baked into the rule itself: someone who is owed money can sue for that debt and, in the same case, ask the court to unwind a transfer of property the debtor made to avoid paying, rather than first winning a judgment on the debt and only then coming back to challenge the transfer. Joining claims this way saves everyone the trouble of separate lawsuits, though the court still decides each claim according to whatever substantive rights apply.
Frequently Asked Questions
Can I add an unrelated claim to a lawsuit I already filed against the same defendant?
Yes. Rule 18 allows a party to join as many claims as it has against an opposing party, whether or not those claims arise from the same events. The claims just need to run between the same two sides.
What is a contingent claim under this rule?
It is a claim that only matters depending on the outcome of another claim in the same case. Rule 18 lets a party join both at once instead of waiting for the first claim to be decided before raising the second.
Does joining claims mean I automatically win on all of them?
No. Joining claims together in one lawsuit is a matter of procedure. The court still evaluates each claim on its own merits and grants relief only to the extent the underlying law supports it.
Can a plaintiff sue for a debt and challenge a fraudulent transfer in the same case?
Yes, the rule specifically allows this. A creditor can pursue a claim for money owed and, at the same time, ask the court to set aside a transfer made to dodge that debt, without first getting a money judgment.
Does this rule apply to counterclaims and crossclaims too?
Yes. Any party asserting a claim, counterclaim, crossclaim, or third-party claim can join multiple claims against an opposing party under this rule.