Definition
Latin. "Of the other part." A phrase used in legal instruments, pleadings, and maxims to designate the opposing or other side in a transaction, document, or proceeding. It identifies the counterparty — the person or party on the other side of a deed, contract, or legal dispute — as distinct from the party first named or the party asserting a claim.
The phrase appears most frequently in its maxim context: Ex antecedentibus et consequentibus fit optima interpretatio — "The best interpretation [of a part of an instrument] is made from the antecedents and the consequents." Here, ex altera parte serves as shorthand within interpretive doctrine, flagging that meaning must be drawn from what comes before and after a disputed passage, not from that passage in isolation.
Common Confusion
EX ALTERA PARTE vs. EX PARTE. These phrases are structurally similar but mean different things. Ex parte means "from one side only" — it signals that a proceeding or order involves only one party, without notice to the other. Ex altera parte means "of the other part" — it acknowledges the existence of an opposing party. A researcher encountering ex parte in a case file is reading about a one-sided proceeding; a researcher encountering ex altera parte in a maxim or deed is reading a reference to the counterparty in a two-sided transaction. Confusing the two distorts both the procedural posture and the interpretive context.
Why It Matters in Research
This term is almost never the primary subject of a case or statute. It appears as a structural phrase within documents and maxims, which means researchers encounter it as a component rather than a target. Several navigational points apply.
First, the phrase surfaces most often inside the maxim ex antecedentibus et consequentibus fit optima interpretatio, which is itself a rule of construction for deeds and contracts. When a historical source cites "2 Inst. 317" in this context, that is a reference to Coke's Institutes — a real and foundational common law treatise. Researchers working on instrument construction disputes in equity or common law will find this maxim cited alongside ex altera parte as its framing device.
Second, in older deed and pleading forms, ex altera parte identifies the second-named party (the "other part") in indentures and conveyances written in the standard bipartite deed format. Deeds of this period routinely began with one party named "of the one part" and the counterparty named "of the other part" — ex altera parte. Researchers reading historical conveyancing materials will see this phrase performing a purely structural, party-identification function rather than a substantive legal one.
Third, the phrase has no significant modern usage. It has been absorbed into plain-English drafting conventions in contemporary instruments and has no independent procedural significance in modern practice. Its appearance in a modern document should prompt the researcher to check whether the source is reproducing archaic form language or is itself a historical document.
Fourth, do not allow superficial similarity to ex parte to lead to a misread of procedural posture in a historical filing. The confusion is easy and the consequences for research accuracy are real.
Historical Dictionary Support
All four shelf sources agree on the core meaning: "of the other part." Burrill, the most historically grounded of the four, traces usage to the Year Books (H. 6 Edw. II), confirming that the phrase is genuinely medieval in origin and was in active use in early common law pleading. This citation is useful for researchers needing to establish when the phrase entered English legal usage.
Black's (both editions) and Rapalje & Lawrence treat ex altera parte primarily as a gateway to the maxim ex antecedentibus et consequentibus, devoting more space to that rule of construction than to the phrase itself. This reflects where the practical legal weight actually falls: the phrase alone carries little independent doctrine, but the maxim it introduces is a substantive canon of interpretation with real force in instrument construction cases.
Rapalje & Lawrence offer the most developed treatment of the maxim, noting that "the context must be most thoroughly looked into before a correct interpretation can be obtained" and characterizing it as "one of the most important rules for the construction of contracts." Researchers working on historical contract or deed disputes should treat the Rapalje & Lawrence entry as the most useful starting point on the interpretive doctrine that ex altera parte commonly introduces.
No shelf source addresses the potential confusion with ex parte, which is a gap worth noting. That conflation risk is a product of modern researchers reading both phrases in Latin without adequate context — a hazard the historical dictionaries did not anticipate because the distinction would have been obvious to their intended audience.
Encyclopedia Cross-Reference
For the ex parte distinction (procedural one-sided proceedings): Constitutional Law Encyclopedia, constitutional_42: Ex parte Young — The Fiction That Permits Suits Against State Officers. For emergency protective order practice where ex parte procedure is central: Family Law Encyclopedia, family_171: Domestic Violence — Emergency / Ex Parte Orders of Protection.