Also known as:Model Rules 3.1 · MR 3.1 · MRPC 3.1 · Rule 3.1 · ABA Model Rule 3.1 · meritorious claims rule
Written by attorneys · grounded in primary & secondary sources — see below
A rule of professional conduct that prohibits a lawyer from bringing or defending a proceeding or asserting or controverting an issue unless there is a basis in law and fact for doing so that is not frivolous. The standard permits a good-faith argument for an extension, modification, or reversal of existing law but bars claims resting on speculation or lacking any reasonable legal or factual foundation.
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Model Codes
Casebooks
Course Outlines
How it applies
Common Examples
2
Copyright Claim Lacking Protectable Elements
Christian asks Frank to sue a major-label artist for copyright infringement. The songs share only a common four-chord progression and a broad romantic theme, with no identical lyrics, melodies, or other protectable expression, and no evidence of access. Frank researches the claim and learns that every circuit requires substantial similarity of protectable elements plus proof of access. Frank declines to file because the absence of any shared protectable expression leaves the complaint without a nonfrivolous basis in law or fact.
Nuisance Suit Without Causation Evidence
Billy and neighbors report respiratory symptoms coinciding with visible factory emissions. State monitoring shows the factory has always operated within permit limits, and no physician links the symptoms to the emissions. Peggy locates older cases allowing nuisance claims despite regulatory compliance but recognizes those decisions required proven injury. Peggy decides not to file because resident testimony alone supplies no factual basis for causation and therefore renders the complaint frivolous.
Common questions
Frequently Asked
4
What standard does Rule 3.1 apply to determine whether a claim is frivolous?+
Rule 3.1 bars a lawyer from bringing or defending a proceeding unless there is a basis in law and fact that is not frivolous. A claim is frivolous if a reasonable lawyer could not make a good-faith argument on the merits or for an extension of existing law. The rule permits creative advocacy that seeks to develop the law when supported by some authority but prohibits filings resting on speculation or lacking any reasonable foundation.
Supporting sources
Does client pressure create a nonfrivolous basis for filing under Rule 3.1?
No. Rule 3.1 requires the lawyer to conduct an independent assessment of legal and factual merit. Client insistence or threats to discharge counsel do not supply a reasonable basis when the claim lacks support in law or fact. Filing under such pressure exposes the lawyer to discipline even if the client believes the claim is valid.
Supporting sources
May a lawyer file a claim to test a novel legal theory under Rule 3.1?+
Yes, provided the theory rests on a colorable argument for extending or modifying existing law. The rule expressly authorizes good-faith arguments for legal change when supported by some authority or factual predicate. A filing is still improper if it lacks any plausible hook in current doctrine or facts.
Supporting sources
How does Rule 3.1 interact with First Amendment protections for the opposing party?+
Constitutional protection for the defendant's conduct can render the proposed claim frivolous. When the lawyer knows the targeted activity constitutes core protected petitioning, filing suit lacks any nonfrivolous basis and subjects the lawyer to discipline under Rule 3.1.
Supporting sources
Professional ResponsibilityLitigation and other forms of advocacy · Meritorious claims and contentionsMPREFoundational