Also known as: material witnesses
Written by attorneys · grounded in primary & secondary sources — see below
A person whose testimony is material to the determination of a disputed issue in a legal proceeding.
Madison Meyers once gave sworn testimony in a workers compensation case describing how a press guard failed to engage. Years later she presides over a products liability suit involving the identical press model and the same malfunction sequence. South Plastics moves to disqualify her because her earlier account addresses a central factual issue now in dispute. The court grants the motion and assigns another judge.
Federal agents arrest Albert Roviaro after an informant participates in a heroin transaction. Roviaro seeks the informant's name to show lack of knowledge. The government refuses disclosure. The Supreme Court reverses the conviction because the informant was a material witness on the key element of knowing possession.
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Abdullah al-Kidd is detained under a material witness warrant while traveling to Saudi Arabia. He sues the Attorney General alleging pretextual use of the warrant. The Supreme Court holds that an objectively reasonable arrest under a valid warrant cannot be challenged on the basis of improper motive even when the detainee is held solely as a material witness.
Edward Lawson is repeatedly stopped and arrested under a California statute requiring persons who loiter to provide identification. He challenges the law as unconstitutionally vague. The Supreme Court invalidates the statute because it fails to give adequate notice of what conduct is required and invites arbitrary enforcement against persons who might be material witnesses.
Victor Feola and others assault federal officers during a narcotics transaction. Feola claims he did not know the victims were officers. The Supreme Court holds that the government need not prove knowledge of the victims' official status to establish conspiracy liability because the officers were material witnesses to the underlying assault.
Chicago police arrest James McCray after an informant provides a tip leading to heroin recovery. McCray demands the informant's name at a suppression hearing. The Supreme Court upholds nondisclosure because the informant was not a material witness at trial and the tip merely supplied probable cause.
A judge must disqualify herself when she previously gave sworn testimony on a fact central to the current proceeding. The prior testimony must concern the same matter now before the court. Testimony given in a separate case or administrative hearing does not trigger disqualification if the factual and legal issues differ.
Supporting sources
Federal law permits detention when the witness's testimony is material and it may become impracticable to secure appearance by subpoena. Detention is not allowed if the testimony can be secured by deposition and detention is unnecessary to prevent a failure of justice. Courts must supervise such detentions and require periodic reports.
Supporting sources
No. The rule requires that the judge have been a material witness concerning the matter now before the court. Testimony given in a distinct proceeding with different parties or issues does not satisfy the standard even if the factual topic overlaps.
Supporting sources
…probable cause). [^maj-13]: Police officers may have a similar power with respect to persons whom they reasonably believe to be material witnesses to a specific crime. See, e. g. , ALI Model Code of Pre-Arraignment Procedure § 110.2(1)(b) (Proposed Official Draft 1975). [^maj-14]: Of course, some reactions by individuals to a…