Also known as: magistrate judge · magistrates judge · magistrates judges · US magistrate judge · federal magistrate judge
Written by attorneys · grounded in primary & secondary sources — see below
A federal judicial officer appointed to assist district judges by performing pretrial and other judicial functions including the review of complaints and the issuance of warrants or summonses.
Federal agents submit a complaint and affidavits against Megan Moore by secure email after hours. The magistrate judge reviews the materials over the phone line and determines probable cause exists. The judge then issues a summons directing Moore to appear rather than ordering an immediate arrest.
Miranda Morales appears before a magistrate judge for a pretrial conference in a civil coverage dispute. Counsel for both sides present detailed factual accounts of the underlying events. The magistrate applies the Federal Rules of Evidence to determine whether those statements may be considered at a later contempt hearing.
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Michael Miller is arrested in the district where the charged offense allegedly occurred. No magistrate judge is available at the courthouse that evening. Officers therefore bring Miller before a state judicial officer for the initial appearance as permitted by the rules.
Musa Mensah moves to disqualify the magistrate judge assigned to a high-stakes commercial case. The motion rests on the judge's prior campaign contributions from one of the litigants. The magistrate examines whether impartiality might reasonably be questioned under the governing statute.
Maria Morales is located abroad after a magistrate judge issues an arrest warrant on a federal complaint. Agents coordinate with foreign authorities to execute the warrant at her hotel. The court later confirms that the warrant's reach extends overseas when a federal statute authorizes the arrest.
Mason McCarthy's real property is seized under a civil forfeiture statute without prior notice or hearing. The magistrate judge later reviews whether the government provided adequate process before depriving McCarthy of his interest. The court holds that notice and an opportunity to be heard were required before the seizure.
A magistrate judge may consider information communicated by telephone or other reliable electronic means when reviewing a complaint or deciding whether to issue a warrant or summons. The judge must place the applicant under oath and may examine the applicant and any person whose testimony supports the application. These procedures ensure the reliability of the information while allowing remote review.
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The Federal Rules of Evidence apply to proceedings before United States magistrate judges. This coverage extends to both civil and criminal matters as well as non-summary contempt proceedings. The rules therefore govern evidentiary determinations made by magistrate judges in the same manner as those made by district judges.
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If the defendant is arrested in the district where the offense was allegedly committed, the initial appearance must be held in that district. A magistrate judge must preside unless one is not reasonably available. In that limited circumstance a state or local judicial officer may conduct the appearance instead.
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…to his material-witness arrest as he was boarding a plane to Saudi Arabia. To secure the warrant, federal officials had told a Magistrate Judge that information "crucial" to Sami Omar al-Hussayen's prosecution would be lost if al-Kidd boarded his flight. Prosecutors never called al-Kidd as a witness, and (as he alleges) never meant…