Evidence & Discovery — Law Library

The rules governing what evidence is admissible at trial and how parties exchange information before trial through the discovery process.

Statutes & Rules

Test for Relevant Evidence (Fed. R. Evid. 401)
Evidence is relevant if it has any tendency to make a fact of consequence more or less probable.
Character Evidence / Prior Acts (Fed. R. Evid. 404)
Character evidence is generally inadmissible to prove conforming conduct; prior bad acts may be admitted for other purposes (motive, opportunity, intent, etc.).
Testimony by Expert Witnesses (Fed. R. Evid. 702)
Governs the admissibility of expert testimony; requires sufficient facts, reliable methods, and proper application.
Duty to Disclose; General Provisions Governing Discovery (Fed. R. Civ. P. 26)
Requires initial mandatory disclosures and governs the scope and limits of all civil discovery.
Discovery and Inspection (Criminal) (Fed. R. Crim. P. 16)
Governs the government's obligation to disclose documents, objects, reports, and prior statements in criminal cases.

Landmark Cases

  • Daubert v. Merrell Dow Pharmaceuticals, 509 U.S. 579 (1993) — Trial judges serve as gatekeepers for expert testimony; scientific evidence must be based on sufficient facts and reliable methodology.
  • Crawford v. Washington, 541 U.S. 36 (2004) — The Confrontation Clause bars admission of out-of-court testimonial statements unless the declarant is unavailable and the defendant had a prior opportunity to cross-examine.
  • Chambers v. Mississippi, 410 U.S. 284 (1973) — Due process may require admission of evidence that would otherwise be excluded under state evidentiary rules when exclusion prevents a meaningful defense.

Key Terms

Hearsay
An out-of-court statement offered to prove the truth of the matter asserted; generally inadmissible with numerous exceptions.
Chain of Custody
The documented record of who has handled evidence from collection through trial.
Subpoena Duces Tecum
A court order compelling a person to produce documents or other evidence.
Interrogatories
Written questions sent to the opposing party that must be answered under oath.
Deposition
Oral testimony taken under oath outside of court, recorded for use at trial.
Work Product Doctrine
Protects materials prepared by an attorney in anticipation of litigation from discovery by the opposing party.