Definition
Ex una parte is a Latin phrase meaning "on one part" or "on one side." It describes a proceeding, instrument, statement, or legal act that involves, proceeds from, or operates in favor of one party only. The phrase is closely allied to ex parte but emphasizes the one-sided nature of a thing — its origin, perspective, or effect — rather than necessarily denoting the procedural mechanics of a hearing conducted without notice to the opposing side.
In practice, the term appears most frequently in two contexts:
1. Proceedings or orders: A matter conducted or decided based on the representations of one party alone, without the other party being heard.
2. Instruments and deeds: A document or conveyance executed or taking effect on one side of a transaction only, as opposed to a mutual or bilateral instrument.
Common Confusion
Ex una parte and ex parte are frequently used interchangeably, and for most practical purposes they overlap. The distinction, where it survives, is one of emphasis. Ex parte is the dominant procedural term in modern law and describes the formal absence of the opposing party from a proceeding. Ex una parte is the older, more literal phrasing — "from one side" — and was used more broadly in pre-modern sources to describe anything one-sided in nature, including instruments and statements, not only court proceedings. Researchers encountering ex una parte in historical texts should not assume it carries the full modern procedural weight of ex parte.
Why It Matters in Research
Ex una parte is a historical term that has effectively been absorbed by ex parte in modern legal usage. Researchers are unlikely to encounter it in contemporary opinions or statutes, but it appears with some regularity in nineteenth-century American and English case law and treatises, particularly in discussions of deed interpretation, evidence, and one-sided contractual instruments.
The Rapalje & Lawrence entry provides the most useful archival signal: the string of citations spans federal and state courts across the mid-to-late 1800s, including Connecticut, Massachusetts, New York, Pennsylvania, Virginia, Alabama, Louisiana, and Minnesota authorities. This distribution confirms the phrase had genuine circulation across jurisdictions before ex parte consolidated the field. A researcher tracing the history of ex parte doctrine through primary sources may find ex una parte used where modern courts would simply write ex parte.
One trap in historical sources: the phrase sometimes appears in Latin passages within opinions that are discussing the interpretation of instruments or statutes — not procedural posture — and in those contexts it means simply "from one side" or "from one party's perspective," without any implication that a court proceeding was conducted without notice. Reading it as a procedural term in those contexts produces a misreading.
The Black's 2nd edition entry is incomplete in the surviving source material ("the exposition of a statute" appears to be a fragment from the surrounding page rather than part of the definition), and researchers should treat that entry with caution and cross-check against Burrill and Rapalje & Lawrence.
Historical Dictionary Support
All four source dictionaries agree on the core translation: "of one part or side; on one side." There is no meaningful divergence on the literal meaning.
Burrill offers the most economical entry, simply providing the Latin gloss. Black's 1st edition adds the companion phrase ex uno disces omnes ("from one you may discern all"), which is a separate maxim and appears to have been included by proximity on the source page rather than conceptual connection — researchers should treat that association as an artifact of the original dictionary's layout, not a meaningful link.
Rapalje & Lawrence is the most substantively useful of the historical sources. Rather than elaborating on the definition, it provides an extensive citation string that anchors the phrase in actual reported decisions. This is characteristic of Rapalje & Lawrence's approach and makes it the preferred starting point for anyone tracing the phrase through nineteenth-century case law.
None of the historical dictionaries distinguish between the procedural and instrumental uses of the phrase. That distinction must be inferred by the researcher from context.
Encyclopedia Cross-Reference
Constitutional Law: Ex parte Young — The Fiction That Permits Suits Against State Officers (The Law Mind Constitutional Law Encyclopedia)
Family Law: Domestic Violence — Emergency / Ex Parte Orders of Protection (The Law Mind Family Law Encyclopedia)
Intellectual Property: The Defend Trade Secrets Act — Federal Civil Action and Ex Parte Seizure (The Law Mind Intellectual Property Encyclopedia)