Definition
The substance of a legal claim or defense, as distinguished from procedural, technical, or formal grounds. A case decided "on the merits" is resolved based on the underlying legal and factual questions — who is right about the actual dispute — rather than on threshold issues like standing, timing, jurisdiction, or procedural defect.
The term operates in two principal contexts:
1. Decision on the merits. A judgment or ruling that reaches and resolves the substantive legal question. Contrasted with dismissals on procedural grounds, which leave the underlying claim unadjudicated. A decision on the merits typically carries preclusive effect (res judicata) in ways that procedural dismissals may not.
2. Affidavit of merits / swearing to merits. A defendant's sworn statement that a good and substantial defense to the action exists, based on the real matter in controversy rather than on technical grounds alone. Historically required in certain procedural contexts to obtain relief such as a continuance or leave to amend. Modern practice has largely replaced this with the certificate of merit, particularly in professional malpractice actions, where a plaintiff must file an expert-supported statement attesting that the claim has substantive basis before the case proceeds.
---
Common Language
Modern common usage (Wiktionary): Intrinsic advantages or qualities of something; the substance of a matter as opposed to its form or procedural trappings.
Historical common usage (Webster's 1913): Desert; that which is deserved; the quality of deserving reward or of being entitled to praise; worth; excellence; virtue.
The common meaning — intrinsic worth or desert — is close enough to the legal meaning to be useful shorthand but misleads in one important direction. In ordinary speech, "merits" implies a positive quality: something has merit if it deserves approval. In law, "the merits" is neutral. A case decided on the merits may be decided against the claimant. The phrase signals that the substantive question was reached, not that the result favored anyone in particular.
---
Common Confusion
MERITS vs. GROUNDS. "Grounds" refers to the legal basis for a claim or ruling and can be either procedural or substantive. "Merits" specifically denotes the substantive side of that divide. A case dismissed for lack of standing is dismissed on procedural grounds, not on the merits. The distinction matters enormously for preclusion analysis and for whether a claim may be refiled.
DECISION ON THE MERITS vs. JUDGMENT ON THE MERITS. These phrases are often used interchangeably but carry distinct technical weight in some procedural contexts. Under the Federal Rules of Civil Procedure, for example, certain dismissals are specifically designated as operating as adjudications on the merits (Rule 41(b)) while others are not. Researchers working with procedural history must attend to which label applies.
---
Why It Matters in Research
The merits/procedure divide is one of the most consequential distinctions in civil litigation, yet historical sources treat it inconsistently. Several navigational points:
Preclusion research. Whether a prior judgment was "on the merits" determines whether claim preclusion bars a subsequent action. Historical cases frequently used "on the merits" loosely, and what counted as a merits determination shifted over time — particularly before the consolidation of law and equity. When tracing preclusion doctrine through 19th-century sources, do not assume the phrase carried the same technical weight it carries today.
The affidavit of merits. This procedural device appears throughout 19th-century common law practice and features prominently in Chitty, Burrill, and Black's. It is largely obsolete as a freestanding requirement in modern American procedure, but its functional successor — the certificate or affidavit of merit in professional malpractice cases — is alive and varies significantly by state. Researchers should not conflate the historical affidavit of merits (a defendant's tool) with the modern certificate of merit (a plaintiff's obligation).
Equity sources. Equity courts developed their own vocabulary around "hearing on the merits," which differed procedurally from common law practice. Sources drawing on chancery tradition may use the phrase in ways that do not map cleanly onto modern civil procedure concepts.
Jurisdictional carryover. Some states still use "swearing to merits" language in older statutory frameworks or local rules. When encountering this phrase in state practice materials, check whether the jurisdiction has modernized the requirement or retained it in modified form.
---
Historical Dictionary Support
The historical sources are in close agreement on the core definition: merits means the substance of a legal position, as opposed to its technical or formal dimensions. Black's (both editions) and Burrill align nearly word for word, defining merits as "matter of substance in law, as distinguished from matter of mere form," with the affidavit of merits as the primary procedural illustration.
Bouvier adds a useful doctrinal refinement — distinguishing a "good defense" (which may rest on technical grounds) from a "defense on the merits" (which must rest on the justice of the cause). This distinction is practically significant and the historical sources do not always make it cleanly.
Rapalje & Lawrence provide the clearest negative illustration: a defense based on misjoinder or nonjoinder of parties, before England's Judicature Acts, was not a defense on the merits even if technically valid. This reinforces the core idea that merits concerns the real matter in dispute, not procedural entitlements. Their entry also signals how the concept evolved in response to procedural reform — a pattern that continued in American practice through the Field Code era and into the Federal Rules.
What the historical dictionaries largely miss: the modern significance of "on the merits" as a trigger for claim preclusion and its role in res judicata analysis. The historical entries focus almost entirely on the defendant-side affidavit of merits context. The broader preclusion dimension — which now dominates how courts and practitioners use the phrase — receives little attention in the shelf sources and must be developed from case law and modern procedural treatises.
---
Jurisdictional Note
The certificate of merit (or affidavit of merit) requirement in professional malpractice cases exists in a majority of states but varies substantially in what it demands, when it must be filed, and what consequences follow from noncompliance. Some states require an expert affidavit at filing; others allow a grace period; others treat noncompliance as grounds for dismissal with prejudice. Researchers working on malpractice procedure should treat this as a jurisdiction-specific inquiry, not a uniform national rule.
---
Encyclopedia Cross-Reference
Torts & Personal Injury Encyclopedia — Professional Malpractice: Certificate of Merit / Affidavit of Merit Requirements (torts_61)
---