What Is Substantial Evidence in Law?

Substantial evidence is a legal concept.
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Substantial evidence is a legal concept that an individual piece of evidence is so sufficient that a reasonable person of sound mind could convict or acquit based on that one piece of evidence alone. Substantial evidence is arguably better known as the “smoking gun” in criminal matters. The concept of substantial evidence is apparent in both civil and criminal law, and can work for or against a particular claim. For the courts to consider a piece of evidence as substantial, the evidence must pass the “substantial evidence test.”


Case law defines substantial evidence as “evidence … [that is] more than a mere scintilla but less than preponderance.” It must go “beyond … mere conjecture.” In application, substantial evidence is essentially so considerable that any reasonable person would agree with the claim that the evidence substantiates. It also fundamentally compels the jury or judge to rule in favor of that claim, because no other evidence or testimony can disestablish the verdict that the substantial evidence itself enforces.


The concept of substantial evidence arises from Section 7803 of the New York Civil Practice Laws and Rules, which permits the courts to review decisions made by administrative agencies and accept them as evidence. In Vega v. Smith (66 NY2d 130 (1985)), Saul Vega, a prisoner in Attica, challenged the prosecution’s use of prison disciplinary board’s records from Vega’s multiple violations of prison rules and procedures, including possession of contraband “classified as a weapon.” On review, the court determined that these records did not violate Vega’s right to due process and that the documents were substantial enough to demonstrate the prosecutors’ claims against him. The case helped form the basis of what would become the substantial evidence test.

Substantial Evidence Test

For a piece of evidence to qualify as substantial, the court must review the evidence to “test” its significance. Judges must find the evidence “reasonable in nature, credible, and of solid value.” The impact of substantial evidence is less than evidence that leaves no doubt, but exceeds mere preponderance. Substantial evidence must actually be considerable proof equal to the burden of proof required in that particular case.

Because the requirements differ depending on the nature of the case, what qualifies as substantial evidence will also differ. What satisfies the substantial evidence in a civil matter may not satisfy the requirements in a criminal matter.

Read More: Types of Evidence at a Crime Scene

Civil Litigation

In civil matters, the requirements for substantial evidence are significantly reduced compared to the requirements for criminal matters. To qualify as substantial evidence, it must meet or exceed the burden of proof for the particular matter into which it is introduced. For example, if the evidentiary burden is preponderance of the evidence, evidence must meet or exceed the preponderance to qualify as substantial.

Criminal Matters

The burden for substantial evidence in criminal matters is considerably higher. Prosecution must prove the defendant is guilty beyond a reasonable doubt, and so the burden of substantial evidence is also beyond a reasonable doubt. Further, the evidence must stand on its own. That is, no additional evidence, including testimony, is required for that piece of evidence to prove the claim.