Also known as:fidem mentitus · fides mentita · breach of faith · perjury
Written by attorneys — see sources below.
An act by which a feudal tenant violates the oath of fealty sworn to a lord. The phrase captures the breach of sworn loyalty that historically carried legal consequences in feudal systems.
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How its tested
Common Examples
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Tenant Swears False Fealty
Tenant Thomas swore an oath of fealty to Lord Lambert. Thomas later sold part of the fief to a third party without consent. The lord brought a writ of forfeiture, treating the sale as fidem mentiri that terminated Thomas's tenure.
Vassal Aids Rival Lord
Vassal Victor secretly aided a neighboring baron who challenged Lord Lambert's title. When the baron invaded, Victor supplied men and arms. The court held Victor's conduct constituted fidem mentiri and declared his lands escheated.
False Homage Ceremony
Tenant Terrence performed homage to Lord Lambert while already bound to another lord. The prior oath rendered the new homage void. Lambert sued for fidem mentiri and recovered the fief by judgment of the manorial court.
Tenant Timothy refused to answer the lord's call to arms during a border skirmish. The lord convened his court and found Timothy guilty of fidem mentiri. Timothy forfeited his holding and was declared an outlaw.
Subinfeudation Without License
Tenant Theodore granted a sub-tenancy to a stranger without obtaining Lord Lambert's consent. The lord claimed the grant itself was fidem mentiri. The manorial rolls recorded the forfeiture of Theodore's estate.
Concealment of Royal Service
Tenant Tabitha hid that she owed knight service to the king rather than to Lord Lambert. When the king demanded service, Lambert discovered the concealment. The court declared the concealment fidem mentiri and seized the tenancy.
Miranda v. Arizona384 U.S. 436 (1966)
In March 1963 Ernesto Miranda was arrested at his home in Phoenix and taken to the police station where he was identified by the complaining witness. He was then questioned by two officers in Interrogation Room No. 2 for two hours. The officers did not advise him of any right to counsel. Miranda signed a typed confession that was introduced at his trial for kidnapping and rape.
On October 14 1960 Michael Vignera was arrested in connection with a Brooklyn robbery. He was taken first to the 17th Detective Squad headquarters in Manhattan and later to the 66th Detective Squad. A detective questioned him for several hours without any advice concerning counsel. Vignera made an oral admission. He was then questioned by an assistant district attorney whose transcribed statement was also introduced at his trial for first-degree robbery.
On March 20 1963 Carl Calvin Westover was arrested by Kansas City police as a suspect in two local robberies. Kansas City police interrogated Westover on the night of his arrest. The next day local officers interrogated him again throughout the morning. Westover was then turned over to FBI agents who questioned him for two to two-and-a-half hours about California robberies and obtained signed confessions. At the time the FBI agents began questioning Westover he had been in custody for over fourteen hours.
On January 31 1963 Roy Allen Stewart was arrested at his home in connection with a series of purse-snatch robberies. During the next five days police interrogated Stewart on nine different occasions without any advice of rights. On the ninth session Stewart confessed. Transcripts of the interrogations were introduced at his trial for kidnapping rape and murder.
The Arizona Supreme Court affirmed Miranda's conviction. The New York courts affirmed Vignera's conviction. The Ninth Circuit affirmed Westover's conviction. The California Supreme Court reversed Stewart's conviction. The Supreme Court granted certiorari in the four cases and consolidated them for argument.
How does the historical meaning of fidem mentiri relate to modern perjury rules?
The phrase originally described a feudal tenant's breach of sworn loyalty to a lord. The concept of broken fealty later influenced the development of perjury as a distinct legal wrong.
Supporting sources
Does a prior inconsistent statement given under oath qualify as fidem mentiri?
No. Fidem mentiri concerns breach of a feudal oath of loyalty, not testimonial inconsistency in later judicial proceedings.
Supporting sources
Can bias evidence show a witness's potential fidem mentiri?
No. Bias impeachment addresses credibility in court. Fidem mentiri addresses violation of a feudal tenant's oath to a lord.
Supporting sources
Why must genetic testing reports be signed under penalty of perjury?
The signature requirement is unrelated to fidem mentiri, which concerns feudal breach of fealty rather than modern authentication rules.
Supporting sources
376 U.S. 254 (1964)
…"the struggle for the right-to-vote," and the legal defense of Dr. Martin Luther King, Jr., leader of the movement, against a perjury indictment then pending in Montgomery. The text appeared over the names of 64 persons, many widely known for their activities in public affairs, religion, trade unions, and the performing…