Definition
Quum quod ago is a Latin maxim of civil and common law meaning, roughly, "when what I do." The phrase is the opening clause of a broader legal principle: when the thing I do cannot take effect in the manner intended, it should be given effect in whatever way it lawfully can. The maxim expresses the interpretive preference for saving the legal act rather than voiding it — courts should not defeat the apparent intention of a party simply because the precise form chosen is ineffective, so long as an alternative form exists that accomplishes a lawful result.
In practice, the maxim supports the principle that a legal instrument — a deed, will, contract, or grant — ought to be construed to give effect to the grantor's or testator's intent wherever possible, rather than rendered wholly void for technical deficiency.
Common Confusion
This maxim is easily confused with a cluster of related Latin interpretive maxims that appear in close proximity in historical legal digests, including quum in testamento ambigue (which governs ambiguous expressions in wills specifically) and ut res magis valeat quam pereat (the maxim explicitly preferring that a thing have effect rather than perish). These are distinct rules. Quum quod ago addresses the mode of operation of a legal act — if one mode fails, try another. Ut res magis valeat is a broader saving canon. The two overlap in effect but differ in scope and origin.
Why It Matters in Research
Researchers encountering this maxim in historical legal materials should be aware of several navigational challenges.
First, the maxim appears in truncated form across historical sources. Black's 2nd edition preserves fragments of surrounding maxims but the full text of the quum quod ago principle itself — typically rendered as quum quod ago non valet ut ago, valeat quantum valere potest — may not appear in full in a single dictionary entry. Researchers should search both under the Q entries and within treatise discussions of construction and interpretation.
Second, the maxim has its roots in Roman law, specifically the Digest (Corpus Juris Civilis), and its reception into English common law was mediated through civilian scholarship and equity practice. When this maxim appears in English or American case law or chancery opinions, it is often cited alongside Broom's Legal Maxims, which was the standard English-language digest of these principles. Broom's treatment, rather than direct Digest citations, is typically what English and American lawyers were actually using.
Third, because the maxim concerns interpretive preference rather than a substantive rule of law, it functions as an argument structure, not a holding. In historical case research, you will find it deployed in argument and in judicial reasoning about construction, not as a standalone rule generating outcomes. It will appear in discussions of wills, deeds, grants, and contract interpretation — particularly where a specific operative clause has failed.
Fourth, the maxim is most active in equity contexts and in will construction cases. Researchers working in those areas should treat this as a related-terms pointer to the broader literature on benign or liberal construction of testamentary instruments.
Historical Dictionary Support
Black's 2nd edition presents this maxim within a sequence of Latin maxims beginning with quum, suggesting the editors organized entries alphabetically within the Latin corpus rather than by subject. The surrounding entry — quum in testamento ambigue aut etiam perperam scriptum est, benigne interpretari et secundum id quod credibile et cogitatum credendum est — is a related but distinct maxim governing ambiguous or erroneous will drafting, citing Digest 34, 5, 24 and Broom's Legal Maxims at page 437. The juxtaposition of these entries in Black's reflects the thematic clustering of liberal construction principles drawn from Roman law.
Historical dictionaries of this period generally present these maxims without extended analysis, leaving the researcher to consult Broom directly for application and illustration. What the dictionary sources miss is the doctrinal pathway by which these maxims moved from the Digest into equity practice and then into common law courts — a history that requires treatise-level sources to trace.
Jurisdictional Note
This maxim was applied across common law jurisdictions that inherited civilian interpretive principles through equity, including England and the United States. Its force in modern American law is largely absorbed into codified rules of construction for wills and contracts; explicit citation to the Latin maxim is rare in contemporary practice but persists in older reported decisions and academic treatments of legal maxims.