Short answer. Section 4 of Rule 8 requires that facts showing capacity to sue or be sued, or authority to sue in a representative capacity, or the legal existence of an organized association made a party, be affirmatively averred — and any challenge to that capacity must be raised by specific denial with supporting particulars.
What the law says
Facts showing the capacity of a party to sue or be sued or the authority of a party to sue or be sued in a representative capacity or the legal existence of an organized association of persons that is made a party, must be averred.
Rule 8, Section 4 — Capacity. Read the full provision →
Capacity and authority must be affirmatively pleaded
Section 4 requires more than a bare assumption of capacity: facts showing the capacity of a party to sue or be sued, or the authority of a party to sue or be sued in a representative capacity, or the legal existence of an organized association of persons made a party, must be averred. This means the complaint (or answer, where relevant) needs to actually state the facts that establish these things, not simply name the party and assume capacity is self-evident from the caption alone.
Challenging capacity requires specificity
The flip side of this requirement protects against vague challenges: a party desiring to raise an issue as to the legal existence of any party or the capacity of any party to sue or be sued in a representative capacity shall do so by specific denial. A blanket denial is not enough to contest capacity — the challenging party must specifically deny it and include such supporting particulars as are peculiarly within the pleader's knowledge, rather than simply asserting the point in general terms without any factual backing. This specificity requirement binds whichever party is raising the challenge, plaintiff or defendant; a party who merely denies capacity 'for lack of knowledge' without more does not satisfy Section 4's demand for particulars.
Why this matters for suing an association
For an entity like an association, this section is the mechanism by which its legal existence — and thus its capacity to be sued as a defendant — gets put into the case record, either affirmatively pleaded by the plaintiff or, if disputed, specifically contested by the defense with particulars. It ensures capacity issues are surfaced clearly early in the case rather than left ambiguous until much later in the proceedings, when resolving them could require reopening matters the parties assumed were already settled. Getting this right at the outset also avoids a later dismissal on the technical ground that the defendant association was never shown to be a suable entity in the first place.