Definition
De malo lacu is a Latin phrase meaning "of the evil pool" or "from the bad lake," used in medieval English law to denote a specific condition or circumstance of physical infirmity — specifically, a debilitating illness or bodily incapacity — that could excuse a party from personal appearance in court. The phrase belongs to a cluster of Latin writs and pleas grouped under the broader heading of essoin de malo, which permitted litigants to send a legal excuse (an essoin) in place of appearing before a tribunal. De malo lacu referred to one variety of such excuse, generally understood to describe a serious illness rendering travel or appearance impossible. It is closely related to, and sometimes treated synonymously with, de malo lecti ("of the sick bed"), though commentators have distinguished between them at various points in the common law's development.
Common Confusion
De malo lacu is easily confused with de malo lecti. The two phrases are closely allied and appear in close proximity throughout the medieval sources. De malo lecti refers specifically to confinement to a sick bed — a narrower and more severe condition. De malo lacu, while also tied to illness and incapacity, was understood by Bracton and subsequent commentators to describe a somewhat earlier or less acute stage of infirmity, though the line between them is not consistently drawn in the sources. Researchers should not treat the two as interchangeable without consulting the specific procedural context of the document under examination.
Why It Matters in Research
This term is almost exclusively a term of medieval English procedural law. Researchers encountering it will be working in the essoin system — the formal structure by which a litigant could excuse non-appearance in court — and will need to situate the phrase within that broader framework to understand what legal consequence attached to the plea.
The essoin system was largely abolished or rendered obsolete by procedural reforms in the nineteenth century, which means de malo lacu will appear only in historical sources: medieval plea rolls, Bracton's De Legibus, Magna Carta commentary, and early common law treatises. It will not appear in modern procedural codes or contemporary case law.
The key research trap here is treating Burrill's truncated entry as complete. Burrill's entry is skeletal — it provides only cross-references (Bracton, fol. 319, 381, 433; Magna Carta, 9 Hen.) without substantive definition. This reflects the difficulty of defining terms whose full meaning existed only within the living procedural practice of medieval courts. Researchers should go directly to the Bracton folio references to recover the operational content of the term. The Magna Carta reference likely points to the provisions governing essoins under the reign of Henry III, where the conditions for valid essoin were among the more contested procedural questions of the period.
Corpus researchers should also be alert to variant spellings and Latinization. Medieval scribal practice was inconsistent, and the phrase may appear with lacus rendered in different case forms depending on the grammatical context of the surrounding text.
Historical Dictionary Support
Burrill's Law Dictionary entry is among the sparsest in that work: it identifies the term as "Mauley" (almost certainly a corrupted or abbreviated note, possibly referencing a case or commentator) and directs the reader to three folio locations in Bracton and to a Magna Carta provision from the reign of Henry III. Burrill offers no independent definition, which is telling — this is a term whose meaning was assumed to be known to practitioners of the medieval common law and was not considered to require elaboration by the mid-nineteenth century.
The Bracton citations (fol. 319, 381, 433) are the primary locus of legal substance. Bracton's treatment of essoins was systematic and distinguished among the various forms of excuse with considerable care; the folio references suggest de malo lacu was addressed in more than one procedural context. The absence of any treatise-level explanation in Burrill reflects the broader pattern for highly technical medieval terms: by the time systematic English legal dictionaries were compiled, the procedural machinery these terms described had long since fallen away.
No other standard historical dictionary in the Law Mind corpus appears to carry a dedicated entry for this term, making Burrill the primary — and essentially only — dictionary-level authority available.
Jurisdictional Note
De malo lacu is a term of medieval English common law and has no operative meaning in any modern jurisdiction. Researchers encountering it should understand that any procedural consequence it carried existed exclusively within the English royal court system prior to the abolition of the essoin system.