Definition
A Latin term appearing in historical English common law with at least two distinct procedural senses:
1. (Writ) A writ directed at a person who had unlawfully removed a bondman or bondwoman from the jurisdiction, preventing the serf from being replevied (recovered through legal process) by their lord. The writ compelled the return of the unfree person to the reach of the law.
2. (Jury procedure) The act or process of sending a jury out to deliberate and render their verdict — that is, the formal dispatch of the jury from the court to form their verdict. Some historical sources render this sense as the "sending out" phase of jury proceedings.
Common Confusion
The term IUM does not correspond to a single coherent modern legal concept. Its two historical meanings — a writ concerning serfdom and a jury-dispatch procedure — are unrelated to each other and neither survived into modern practice in recognizable form. Bouvier's cross-reference to PROCEDENDO suggests some editors treated IUM as overlapping with or reducible to that writ; researchers should not assume the entries under IUM in different dictionaries refer to the same proceeding.
Why It Matters in Research
IUM is an obsolete Latin term encountered almost exclusively in historical English legal sources, particularly in materials predating the abolition of serfdom and the formalization of jury procedure in modern codes. Researchers are most likely to encounter it in citations to Registrum Omnium Brevium (Reg. Orig.) or in analytical works on early common law pleading and jury practice such as Hallifax's Analysis of the Civil Law.
The dual meaning is a research trap: a reader encountering "IUM" without context cannot determine from the term alone whether the source is discussing a writ for the recovery of a serf or the procedural moment of jury dispatch. The surrounding procedural context — whether the record concerns villeinage or jury management — is the only reliable guide.
Bouvier's cross-reference to PROCEDENDO is worth pursuing: procedendo is a better-documented writ ordering a lower court to proceed to judgment, and Bouvier may have viewed IUM in its jury-dispatch sense as functionally related. However, that connection is not established in other standard authorities and should be treated as Bouvier's editorial interpretation, not settled doctrine.
Because IUM concerns serfdom in one of its senses, it belongs to a cluster of writs (alongside de nativo habendo and de libertate probanda) that presupposed the legal status of villeinage — a status that ceased to have practical legal relevance in England well before the early modern period. Any research touching this sense of IUM is necessarily historical and concerns the feudal property law of persons.
Historical Dictionary Support
Black's Law Dictionary treats IUM solely as the writ concerning the removal of a bondperson, citing Reg. Orig. 79. Bouvier's Law Dictionary presents two entries: a brief cross-reference to PROCEDENDO (without elaboration), and a separate definition connecting IUM to the sending-out of a jury, citing Burrill's law dictionary and Hallifax's Analysis. The two dictionaries do not contradict each other so much as they capture different senses without acknowledging the ambiguity. Neither source offers procedural detail sufficient for a researcher to reconstruct how the writ or the jury-dispatch process operated in practice. Hallifax's reference is to his analytical treatment of jury procedure in civil proceedings; Burrill's corroboration indicates the jury-dispatch meaning had some currency among 19th-century American legal lexicographers working from English common law sources. Neither sense appears in modern legal dictionaries, confirming the term's complete obsolescence.
Jurisdictional Note
IUM in both senses is a feature of historical English common law with no recognized counterpart in modern American, English, or Commonwealth legal systems. Its appearance in American sources such as Bouvier reflects the incorporation of English common law terminology into 19th-century American legal scholarship, not any independent American legal development.