(a) In general. A party asserting a claim, counterclaim, cross-claim, or third-party claim may join, as independent or alternative claims, as many claims as it has against an opposing party.
Rule 18.Joinder of claims
Title IV: Parties · Last amended July 1, 2016 · Last verified July 14, 2026
In one sentenceRule 18 lets a party pack every claim it has against an opponent into one action, including claims that only make sense if another claim is resolved a certain way first.
Full Text of Rule 18
(b) Joinder of contingent claims. A party may join two claims even though one of them is contingent on the disposition of the other; but the court may grant relief only in accordance with the parties' relative substantive rights. In particular, a plaintiff may state a claim for money and a claim to set aside a conveyance that is fraudulent as to that plaintiff, without first obtaining a judgment for the money.
Amendment History
(Adopted March 1, 2016, effective July 1, 2016.)
Plain-English Summary
Rule 18 clears away any worry about mixing claims in a single lawsuit. Once a party has an opponent properly before the court, whether asserting a claim, counterclaim, cross-claim, or third-party claim, it can add every other claim it has against that same opponent, related or not. There's no requirement that the claims share a common set of facts; the rule trusts parties to combine everything into one case rather than filing separate suits over the same relationship or dispute.
The rule also covers claims that depend on each other. A party can join a claim that only matters if a different claim is resolved a certain way, for instance a claim for money alongside a claim to undo a fraudulent transfer, without first winning a judgment on the money claim. The court sorts out how much relief each claim supports once the case is decided, but nothing stops a party from putting all of it in front of the court at once.
Frequently Asked Questions
Do my claims against the same opponent need to be related to be joined?
No. Rule 18 doesn't require any connection between the claims a party brings against the same opposing party.
Can I bring a counterclaim and a totally unrelated claim in the same case?
Yes, Rule 18 allows a party to join as many independent or alternative claims as it has against an opposing party.
What is a contingent claim under Rule 18?
It's a claim that only matters depending on how a different claim in the same case turns out.
Do I need a judgment on my main claim before adding a claim to undo a fraudulent transfer?
No. A plaintiff can join a claim for money with a claim to set aside a fraudulent conveyance without first obtaining judgment on the money claim.
Does Rule 18 apply to third-party claims too?
Yes. Third-party claims are among the claim types the rule allows a party to expand with additional claims against the same opponent.
Source & verification. Rule text
are reproduced verbatim from the Idaho Rules of Civil Procedure, adopted by the
Supreme Court of Idaho. Last verified July 14, 2026. ·
Official source
Also known as: joinder of claims idahocombine claims in one lawsuitcounterclaim rulemultiple claims same casecontingent claim joinder