There are four traditional types of evidence: real, demonstrative, documentary, and testimonial. Some rules of evidence apply to all four types and some apply only to some or one of them.

These rules govern the introduction of evidence in proceedings, both civil and criminal, in Federal courts. While they do not apply to suits in state courts, the rules of many states have been closely modeled on these provisions.

Outlines basic procedures to obtain the most reliable and accurate information from eyewitnesses. A few of the topics discussed in this NIJ Research Report include procedures for interviewing the witness and procedures for witness identification of suspects.

The law of evidence governs the use of testimony (e.g., oral or written statements, such as an affidavit) and exhibits (e.g., physical objects) or other documentary material which is admissible (i.e., allowed to be considered by the trier of fact, such as jury) in a judicial or administrative proceeding (e.g., a court of law).