Definition
In law, "certain" carries a precise technical meaning that goes beyond ordinary confidence or assurance. It describes something that is ascertained, definite, identified, or capable of being made definite from information already at hand — without ambiguity, mistake, or need for further inquiry.
The term operates in several legal contexts:
1. As applied to obligations and debts: A debt or obligation is certain when its amount, subject matter, or terms are fixed and identifiable. A sum is certain if it can be computed from the face of the instrument without resort to extrinsic evidence.
2. As applied to pleading and description: A legal description, claim, or allegation is certain when it identifies the subject matter with enough specificity that no reasonable doubt remains about what is intended. Burrill distinguishes the term from general and indefinite: certain means limited, specified, and defined.
3. As applied to dates, instruments, and events: A certain date or instrument is one that is established and known — not contingent, approximate, or open to inference.
Critically, "certain" in law does not always require present, fixed certainty. Black's formulation — "capable of being identified or made known, without liability to mistake or ambiguity, from data already given" — permits a thing to be legally certain even if not yet reduced to a specific number or fact, provided the mechanism for reaching that specificity is clear and determinable. This is sometimes called reducible certainty.
Common Language
Modern common usage (Wiktionary): Wiktionary's primary entries for "certain" in ordinary use describe it as meaning sure, confident, or beyond doubt — often describing a state of mind. The legal entry provided is a surname entry, which is inapplicable here.
Historical common usage (Webster's 1913): "Assured in mind; having no doubts; free from suspicions concerning." Also: "Not to be doubted or denied; established as a fact."
The gap matters. Ordinary English locates certainty in a person's mental state — you feel certain, you are certain. Legal certainty locates the quality in the thing itself, or in the instrument, description, or obligation. A contract sum can be legally certain even if the parties are subjectively unsure what it is, so long as it is determinable by formula or reference. Conversely, a fact a witness feels completely certain about may be legally uncertain if it rests on unreliable grounds. Anderson's note that jurors should not equate personal doubt with reasonable doubt reflects exactly this gap.
Common Confusion
CERTAIN vs. DEFINITE vs. ASCERTAINED: These terms are often used interchangeably in legal writing but carry different emphases. Definite stresses boundaries and limits. Ascertained stresses that the fact or amount has been determined through inquiry. Certain, as Black's makes explicit, can encompass both present definiteness and future ascertainability — it is the broadest of the three in legal usage. A sum is certain if it is ascertainable, even if not yet ascertained.
CERTAIN vs. ABSOLUTE: Certain describes the quality of identification or determination; absolute describes the quality of conditionality. An obligation can be certain (as to amount) but not absolute (as to whether it will ever arise).
Why It Matters in Research
Researchers will encounter "certain" as a term of art in at least three distinct bodies of doctrine, and conflating them produces research errors.
In contracts and negotiable instruments, certainty of terms is a threshold requirement. Older cases and treatises use "certain sum" as a term of art with specific meaning under bills and notes law. Research into pre-UCC materials must account for the fact that certainty requirements were more rigid than modern rules: historical sources may treat an instrument as non-negotiable for failures of certainty that modern law would excuse.
In pleading, "certainty to a common intent" and "certainty to a particular intent" were formal pleading categories with precise meanings in common law practice. Burrill's reference to Stephens on Pleading reflects this framework. Researchers using early American or English case law on pleading sufficiency must recognize that "certain" in that context invokes a structured doctrinal vocabulary, not simply a general standard of clarity.
In property descriptions, "certain" appears frequently in deeds and grants. A description that identifies land by reference to monuments or adjoining owners may be legally certain even though the precise metes and bounds are not stated on the face of the document. Researchers tracing title questions in early land records should apply the reducible-certainty standard, not the lay meaning.
The Anderson's note on jury instructions — that "uncertain" may include any doubt, reasonable or unreasonable, and that jurors should not be instructed that personal uncertainty requires acquittal — is a reminder that legal certainty and subjective conviction are different measures. This distinction becomes relevant in researching historical jury charge cases.
Historical Dictionary Support
The three shelf sources agree on the core: certain means definite, specified, and identifiable, as opposed to obscure, general, or indefinite. Burrill's taxonomy — clear vs. obscure, particular vs. general, limited vs. indefinite — is the most analytically structured and most useful for understanding how the term operated in pleading contexts. Black's is the most practically useful because it introduces the reducibility standard explicitly: "capable of being identified or made known... from data already given." This formulation has the widest application across modern research contexts.
Anderson's entry is the thinnest but contributes something the others miss: the criminal law dimension of certainty in the context of credibility and doubt. This is an underappreciated application and one that historical sources generally do not integrate into their treatment of "certain" as a property or contract term.
None of the three sources adequately address the jurisdictional variation in how certainty requirements have been applied to negotiable instruments, nor do they account for the significant doctrinal shifts introduced by the Uniform Commercial Code and its predecessors.