A material fact in law is one significant enough to affect a legal decision or outcome. The U.S. Supreme Court’s working definition, drawn from Kungys v. United States, is that a fact or statement is material if it has “a natural tendency to influence, or is capable of influencing,” the decision-maker it was directed to.1Justia U.S. Supreme Court Center. Kungys v. United States, 485 U.S. 759 (1988) The same idea runs through almost every area of American law: whether a contract breach is bad enough to end the deal, whether a lie under oath is a crime, whether a company hid something investors needed to know, whether a seller had to tell you about the leak in the basement.
Materiality is not a single rule. It is a threshold question that gets asked over and over, in different settings, with the same underlying logic: did this fact actually matter?
How Courts Decide Whether a Fact Is Material
Courts use an objective test. The question is not what a particular person says they cared about, but what a reasonable person in the same position would have considered important. A securities plaintiff cannot claim that an obscure footnote was material to them personally; the test is whether a reasonable investor would have found it significant. A buyer upset by a contract breach cannot make the breach material just by being upset. It has to be the kind of breach that would matter to a reasonable party in the same deal.
Courts also judge materiality at the time the decision was made, based on what was knowable then, not with the benefit of hindsight.
Within that objective framework, a few categories of evidence do most of the work:
- Economic impact. A breach causing substantial financial loss is more likely to be material than one with trivial cost. Information capable of moving a stock price or changing an investment decision weighs heavily in securities cases.
- Effect on the core decision. Would the fact have changed what someone did? In fraud, that means asking whether a reasonable person would have acted differently. In perjury, it means asking whether the lie could have steered the proceeding another way.
- Timing. Information disclosed on the eve of a merger can be material because it arrives when investors are making high-stakes decisions. A breach discovered early in a contract’s life may be treated differently than the same breach surfacing after most of the performance is done.
- Intent. Deliberate concealment is strong evidence of materiality. If someone went out of their way to hide a fact, courts reasonably infer the fact mattered. The SEC treats intentional misstatements as presumptively material for exactly that reason.2U.S. Securities & Exchange Commission. SEC Staff Accounting Bulletin No. 99 – Materiality
Materiality Is Not the Same as Relevance
People often use the two words interchangeably. They are not identical. The Federal Rules of Evidence deliberately avoid “material” and instead ask whether evidence concerns a “fact of consequence in determining the action,” because “material” had become too ambiguous from overuse.3Legal Information Institute (LII) / Cornell Law School. Federal Rules of Evidence Rule 401 – Test for Relevant Evidence Relevance is broader: any evidence that nudges a fact slightly more or less probable is relevant. Materiality sets a higher bar, asking whether the fact actually matters to the outcome. Evidence can be relevant without being material. Material evidence is always relevant.
Material Facts in Summary Judgment
Most civil litigants first meet the word “material” in a summary judgment motion. Federal Rule of Civil Procedure 56 directs a court to grant summary judgment when there is “no genuine dispute as to any material fact” and the moving party is entitled to judgment as a matter of law.4Legal Information Institute (LII) / Cornell Law School. Federal Rules of Civil Procedure Rule 56 – Summary Judgment In Anderson v. Liberty Lobby, Inc., the Supreme Court said a fact is material only if it “might affect the outcome of the suit under the governing law.”5Justia U.S. Supreme Court Center. Anderson v. Liberty Lobby, Inc., 477 U.S. 242 (1986) Factual disputes that are irrelevant or unnecessary do not count, no matter how hotly contested.
The substantive law of each case defines which facts qualify. In a negligence case, whether the defendant owed a duty of care is material; what color shirt the plaintiff wore that day is not. If every disagreement in the record involves facts that would not change the result, the judge can decide without a trial. If a genuine dispute exists over a fact that would, the case has to go to a jury.
Material Breach and Material Adverse Change in Contracts
A material breach is one serious enough that the non-breaching side can walk away from the whole agreement, not just sue for damages. Courts ask whether the breach defeated the core purpose of the contract or deprived the other party of a benefit they reasonably expected. Minor slip-ups, like a one-day late delivery when timing was not critical, generally fall short. The Restatement (Second) of Contracts weighs factors including the extent of the harm, the breaching party’s good faith, and how much performance had already been completed.
For sales of goods, the Uniform Commercial Code adjusts the standard by contract type. Single-delivery contracts follow the “perfect tender” rule, letting a buyer reject goods that “fail in any respect to conform to the contract.”6Cornell Law School. UCC 2-601 – Buyers Rights on Improper Delivery Installment contracts raise the bar: a defect in one shipment only breaches the whole deal if it “substantially impairs the value” of the overall contract under UCC § 2-612.7Cornell Law School. UCC 2-612 – Installment Contract Breach That “substantial impairment” phrase is the UCC’s version of materiality.
In mergers and acquisitions, deal contracts almost always carry a Material Adverse Change (MAC) or Material Adverse Effect clause, letting a buyer exit if something happens between signing and closing that fundamentally damages the target’s business, financial condition, or earning potential. Courts have set the threshold deliberately high: the change must be durationally significant, threatening long-term earnings rather than one bad quarter. MAC clauses also typically carve out general economic downturns, industry-wide disruptions, legal changes, and natural disasters unless the target was hit disproportionately. Successfully invoking a MAC is rare and requires evidence of a severe, lasting decline.
Materiality in Securities Law
Securities law has the most fully developed materiality framework. In TSC Industries, Inc. v. Northway, Inc., the Supreme Court held that a fact is material if there is “a substantial likelihood that a reasonable shareholder would consider it important” in making an investment decision.8LII / Legal Information Institute. TSC Industries, Inc. v. Northway, Inc., 426 U.S. 438 (1976) Basic Inc. v. Levinson applied the same standard to Rule 10b-5 fraud, adding that the information must have “significantly altered the total mix of information” available to investors.9Justia U.S. Supreme Court Center. Basic, Inc. v. Levinson, 485 U.S. 224 (1988)
The “total mix” idea is what keeps securities materiality from collapsing into a bright-line test. A fact does not have to be the single reason a reasonable investor would buy or sell. It just has to be the kind of thing a reasonable investor would want to know when weighing the choice.
The SEC’s Staff Accounting Bulletin No. 99 goes further and makes clear that a numerical threshold alone is not enough.2U.S. Securities & Exchange Commission. SEC Staff Accounting Bulletin No. 99 – Materiality A misstatement below five percent of a line item can still be material based on qualitative factors, including:
- Hiding a change in earnings trend, or turning a loss into a gain.
- Concealing a failure to meet analyst consensus forecasts.
- Affecting whether executives qualify for bonuses or incentive compensation.
- Affecting the company’s ability to meet loan covenants or regulatory requirements.
- Concealing an unlawful transaction.
Materiality in Criminal Law
Perjury
Federal perjury under 18 U.S.C. § 1621 applies only when the false statement involves a “material matter.”10Office of the Law Revision Counsel. 18 USC 1621 – Perjury Generally Kungys supplies the test: a lie is material if it had “a natural tendency to influence, or was capable of influencing, the decision of the decisionmaking body to which it was addressed.”1Justia U.S. Supreme Court Center. Kungys v. United States, 485 U.S. 759 (1988) Prosecutors need not prove the lie actually changed the outcome. A false statement to a grand jury can be material if it could have shifted the investigation, even if the jury ultimately reached the correct result. The standard is broad enough to cover lies about collateral matters like a witness’s own credibility, and the tribunal’s disbelief does not undo materiality.
Fraud
Federal fraud statutes, including wire and mail fraud, do not spell out materiality in their text. In Neder v. United States, the Supreme Court held that materiality is an inherent element of all federal fraud offenses because common-law fraud has always required a misrepresentation of material fact. The Court adopted the Restatement (Second) of Torts definition: a matter is material if a reasonable person would attach importance to it in deciding what to do, or if the speaker knows the listener is likely to consider it important even if most people would not.11Justia U.S. Supreme Court Center. Neder v. United States, 527 U.S. 1 (1999) Puffery and exaggeration no reasonable person would rely on fall outside criminal fraud precisely because they are not material.
Obstruction of Justice
The federal obstruction statute reaches conduct that “influences, obstructs, or impedes” the administration of justice.12Office of the Law Revision Counsel. 18 USC 1503 – Influencing or Injuring Officer or Juror Generally When the obstructive conduct is a false statement, the government must prove the statement was material and sufficiently connected to the judicial proceeding. Lying to an investigator who may or may not testify to a grand jury, for instance, may not establish the required link.
Brady and the Defendant’s Side of Materiality
Materiality also protects defendants. Under Brady v. Maryland, prosecutors must turn over evidence favorable to the accused when that evidence is material to guilt or punishment, regardless of good or bad faith. Strickler v. Greene sets out three requirements for a Brady violation: the evidence must be favorable, the prosecution must have suppressed it, and the suppression must have caused prejudice.13Justia U.S. Supreme Court Center. Strickler v. Greene, 527 U.S. 263 (1999) Evidence is material under Brady when there is a “reasonable probability that, had the evidence been disclosed to the defense, the result of the proceeding would have been different.” The question is not whether a different verdict was more likely than not, but whether the trial produced a verdict “worthy of confidence.” This is the materiality standard most often litigated in post-conviction appeals.
Material Defects in Real Estate
Sellers of residential property in most states must disclose material defects they know about before closing. A material defect is one that would affect a buyer’s decision to purchase or the price they would pay. Hidden structural damage, a history of flooding, a faulty foundation, and contaminated water are classic examples. Cosmetic issues or defects a buyer could spot during a normal inspection typically do not qualify.
Failing to disclose carries real consequences. A buyer who discovers an undisclosed material defect after closing may sue for fraud, negligent misrepresentation, or rescission, depending on state law. Claims can also reach real estate agents who knew and stayed silent. Required disclosures and deadlines to sue vary by state, so local requirements should be checked early.
Material Misrepresentation in Insurance
Insurance applications are built on the information you give the insurer. A false statement or omission that would have changed the insurer’s decision to issue the policy, or the price, is a material misrepresentation. Understating your driving record on an auto application or leaving a prior cancer diagnosis off a life insurance form are typical examples.
The insurer’s primary remedy is rescission, treating the policy as though it never existed. If the insurer rescinds, it owes no claims, though it must return the premiums. Most states limit the window for rescission. Life and health policies commonly include a two-year contestability period, after which the insurer generally cannot void the policy for application misstatements short of outright fraud. States differ on how much intent an insurer must show, from proving the misrepresentation was intentional to simply proving it changed the risk the company agreed to insure.
Material Falsity in Defamation
Defamation uses materiality to separate damaging falsehoods from harmless errors. Under the substantial truth doctrine, a statement is not legally false if its “gist” or “sting” is true, even when some details are wrong. The test is whether the inaccuracy would leave a different impression on the reader or listener than a fully accurate version would. If the core allegation is true and the errors are peripheral, the statement is substantially true and will not support a defamation claim.
Saying someone was arrested “Tuesday evening” when the arrest actually happened Wednesday morning is not material if the fact of the arrest is accurate. Changing the nature of the charge, the identity of the person, or the circumstances in a way that makes the statement more damaging crosses into material falsity, and the defamation claim can proceed.