Definition
RESPONSE has two distinct legal meanings, operating in largely separate contexts.
1. Procedural/pleading sense. A formal written answer filed by a party in response to a motion, petition, or other court filing. In this usage, a response is a pleading-adjacent document that addresses the arguments or allegations of the initiating party — not the complaint itself (which draws an answer), but a subsequent filing contesting a motion, brief, or application. Many court rules set specific deadlines for responses to motions, making the term a term of procedural art with rule-governed consequences.
2. Environmental law sense. In federal environmental law — particularly under CERCLA (the Comprehensive Environmental Response, Compensation, and Liability Act) — "response" is a defined statutory term encompassing the full range of actions taken to address a hazardous substance release or threatened release. This includes both removal actions (short-term cleanup) and remedial actions (long-term site remediation), as well as enforcement activities and oversight costs. The distinction matters enormously for cost recovery litigation.
3. Historical/judicial sense. Black's Law Dictionary preserves an older, narrower usage: the opinion of a court on a special case — a sense largely obsolete in modern American practice but present in older English and ecclesiastical legal sources.
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Common Language
Modern common usage (Wiktionary): An answer or reply; the act of responding to a question or statement.
Historical common usage (Webster's 1913): The act of responding; an answer or reply; also, a reply to an objection in formal disputation.
The common and legal meanings share a root, but diverge in consequential ways. In procedural law, a "response" is not simply any reply — it is a formal document subject to court rules governing timing, format, and waiver. Failure to file a response can result in motions being granted as unopposed. In CERCLA practice, "response" is a technical statutory category that determines whether costs are recoverable and from whom — the word's everyday sense of "a reply" provides no guidance here.
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Common Confusion
RESPONSE vs. ANSWER: In federal civil procedure, an "answer" is the formal responsive pleading to a complaint. A "response" typically refers to opposition to a motion or other filing — not the pleading that responds to the initial complaint. Some courts use the terms interchangeably in local rules, which can create confusion when reading historical dockets or rules from other jurisdictions. Researchers should not assume these terms are synonymous across courts or time periods.
RESPONSE vs. REPLY: In motion practice, a "response" is typically the opposing party's filing, while a "reply" is the moving party's subsequent filing addressing the response. The sequence — motion, response, reply — is procedurally significant and deadline-driven. Historical sources may use these terms without that precision.
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Why It Matters in Research
Researchers face three distinct traps with this term.
First, the procedural meaning is highly local. Court rules, local rules, and standing orders vary significantly in how they use "response" versus "opposition," "answer," or "reply." A filing deadline tied to "response" in one court's rules may not translate to another. When researching historical dockets or older procedural materials, verify how the specific court used the term at the relevant time.
Second, the CERCLA statutory definition is the dominant legal meaning in environmental law research and controls cost recovery analysis. The statute defines "respond" and "response" at 42 U.S.C. § 9601(25), and courts have interpreted those definitions extensively. Researchers working in CERCLA materials should treat "response costs" as a term of art with a specific statutory and regulatory meaning — not a general reference to any expense incurred in addressing contamination.
Third, Black's historical definition — "the opinion of a court of law on a special case" — reflects a procedure associated with certain courts of equity and ecclesiastical courts that has no direct modern American counterpart. Researchers encountering this usage in older English or early American sources should not assume it carries its modern procedural meaning.
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Historical Dictionary Support
Black's entry is brief and preserves only the archaic judicial sense: "the opinion of a court of law on a special case." This definition is incomplete for any modern research purpose. It reflects a historical English practice — the rendering of opinions in response to referred questions — that does not correspond to any standard American procedural mechanism.
Notably, Black's omits both the procedural motion-practice meaning and the CERCLA statutory definition entirely, which reflects the dictionary's historical snapshot rather than current legal usage. Researchers relying on Black's alone will miss the two most practically significant modern senses of the term.
Webster's 1913 aligns with the ordinary-language meaning and adds the formal disputation sense (a reply to an objection), which foreshadows the procedural usage but does not capture its rule-governed, deadline-driven character.
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Jurisdictional Note
Federal courts governed by the Federal Rules of Civil Procedure use "response" primarily in the motion-practice context, with deadlines set by FRCP 6 and local rules. State courts vary widely — some use "opposition," some use "response," and some treat the terms interchangeably. In CERCLA litigation, "response" is a federal statutory term with uniform definitional authority, though its application in specific cost-recovery contexts has generated a substantial body of circuit-level interpretation.
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Encyclopedia Cross-Reference
CERCLA — Comprehensive Response, Liability, and the Superfund Framework (Law Mind Environmental & Energy Law Encyclopedia)
CERCLA Liability — Potentially Responsible Parties and Defenses (Law Mind Environmental & Energy Law Encyclopedia)
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