The law of criminal evidence governs how parties, judges, and juries offer and then evaluate the various forms of proof at trial. In some ways, evidence is an extension of civil and criminal procedure. Generally, evidence law establishes a group of limitations that courts enforce against attorneys in an attempt to control the various events that the trial process presents in an adversarial setting.

Why the Law of Criminal Evidence Matters

There are many arguments in favor of evidence law. Here are five of the most common ones:

1. To ameliorate pervasive mistrust of juries
2. To further legal or social policies relating to a matter being litigated
3. To further substantive policies unrelated to the matter in suit
4. To create conditions to receive the most accurate facts in trials
5. To manage the scope and duration of trials

Federal Rules of Evidence: Overview

In the United States, the federal courts must follow the Federal Rules of Evidence (FRE). State courts, on the other hand, generally follow their own rules, which are generally imposed by the various state legislatures. The FRE is the most influential body of American evidence law. The FRE encompasses the majority of the laws of criminal evidence in 68 brief sections. Its language is accessible, easy to read, and mostly free of technical jargon and complicated cross-referencing. The FRE has been enormously influential in the development of U.S. evidence law. This influence in part is a result of its brevity and simplicity.

Before 1975, U.S. evidence law was mostly a creature of the common law tradition. The FRE was drafted and proposed by a distinguished advisory committee composed of practitioners, judges, and law professors appointed by the United States Supreme Court. Just 20 years after the FRE was adopted in the federal system, almost three-quarters of the states had adopted codes that closely resemble the FRE.

The FRE applies in all federal courts in both criminal and civil cases. Understanding some of the basic provisions of the FRE will enable most people to figure out what's going on at trial, even if there are deviations between the FRE and applicable state laws criminal of evidence.

Rules of Evidence

There are different types of evidence that can be used in a criminal trial, and a variety of rules that govern evidence. Some common concepts that come up when discussing the rules of evidence are:

• Circumstantial Evidence: This isn't what you would call "smoking gun" evidence, but rather some piece of information that strongly infers a set of circumstances. For instance, video surveillance showing that the defendant was on the same city block where a crime was committed at around the same time would be circumstantial evidence.
  
• Corroborating Evidence: Evidence that strengthens another piece of evidence, even if it isn't directly related to the crime. For example, a witness claims John was at the scene of the crime at a particular time. If another witness has proof that John failed to show up to work at that same time, then it could be considered corroborating evidence.
  
• Hearsay: This isn't given under oath or offered as official evidence, but merely stated out of court. For example, Fred says he heard that John was in a street gang; but without any evidence, Fred's statement is merely hearsay (and not admissible).
  
• Exclusionary Rule: This rule of evidence applies to that which was obtained in violation of the defendant's constitutional rights. Seizing property without a warrant often is considered a violation and thereby subject to the exclusionary rule.

Get Legal Help Understanding the Law of Criminal Evidence

If you're involved in a criminal case, evidence -- including physical evidence as well as witness testimony -- will be crucial to how the jury decides the outcome. But not all evidence is admissible and each jurisdiction is governed by strict rules for how evidence is treated in a case. For this reason, it's best to contact a local criminal defense attorney who can present the best defense and ensure that the prosecution is complying with the law of criminal evidence.