Definition
A Latin term meaning "day," appearing in legal usage almost exclusively as part of compound phrases rather than as a standalone term. In legal Latin, *diem* is the accusative form of *dies* (day) and functions as a building block for several doctrines and formulas. Its two principal legal contexts are:
1. Per diem — "by the day" or "for each day." Used to express a daily rate of compensation, accrual of damages, or accumulation of some legal consequence over time.
2. Year and a day — historically expressed in Latin formulas incorporating *diem* (e.g., *per annum et diem*), this rule fixed a deadline of one year and one day as the outer limit for certain legal consequences to attach, most notably in the common law of homicide.
Because *diem* has no freestanding legal definition — it derives meaning from its surrounding phrase — researchers should pursue the compound terms directly. This entry primarily serves as a pointer and disambiguation guide.
Common Language
Modern common usage (Wiktionary): Listed primarily as a surname; the word *diem* as a standalone English term is not in common use, though *carpe diem* ("seize the day") is a widely recognized Latin phrase.
Historical common usage (Webster's 1913): Not entered as a standalone English term; treated as Latin.
The gap here is not between common and legal meaning but between how the word appears in research sources. A researcher encountering *diem* in an old pleading, statute, or Latin maxim may not recognize it as a simple inflected form of "day" and may search for it as if it were a term of art. It is not. Its legal significance flows entirely from the phrase it completes.
Common Confusion
Diem is sometimes encountered in digests and indices as an apparent headword when the underlying concept is *per diem* or the year-and-a-day rule. Researchers should not treat *diem* as a self-contained doctrine. Additionally, *dies* (the nominative form) appears in other legal phrases — *dies non*, *dies juridicus*, *dies a quo* — that are distinct concepts. Finding *diem* in a source does not imply the year-and-a-day rule is at issue; context of the surrounding phrase is essential.
Why It Matters in Research
The primary research value of this entry is navigational. In historical legal sources — particularly Latin pleadings, early English statutes, and common law treatises transcribed or indexed by Burrill and similar dictionaries — *diem* appears in abbreviated or fragmentary form. Researchers working in the Law Mind corpus may encounter the term in one of two live research contexts:
First, in damages research, *per diem* arguments are a recognized and contested method of calculating pain and suffering awards in tort cases. The Law Mind Torts encyclopedia addresses this directly. Understanding that *per diem* is a Latin construct meaning "per day" is essential to following the argument's logic and its critics' objections.
Second, in criminal law history, the year-and-a-day rule — which required that a victim die within a year and a day of the defendant's act for homicide liability to attach — was expressed in Latin formulas using *diem* in older sources. The rule has been abolished in most American jurisdictions and in England, but it surfaces in historical case research and in discussions of causation doctrine. Researchers working in pre-twentieth-century criminal law sources should be alert to its presence.
Burrill's brief entry ("for one day; for a year and a day") efficiently captures both contexts, though it offers no guidance on the practical legal consequences of either.
Historical Dictionary Support
Burrill's Law Dictionary provides a minimal but accurate entry, confirming that *diem* in legal usage carried both a general "one day" sense and a specific reference to the year-and-a-day formula. The brevity of the entry reflects the term's nature: it is a grammatical component, not a doctrine. Historical dictionaries uniformly treat the compound phrases — *per diem*, *annus et dies* — as the operative entries. Burrill's choice to list *diem* separately is useful for researchers working from Latin indices but should not be read as indicating that the word itself carried independent legal weight.
No meaningful divergence exists among historical sources on this point. The entry is essentially stable across the dictionaries that address it at all.
Jurisdictional Note
The year-and-a-day rule, the most substantive doctrine historically associated with *diem* formulas, has been abolished by statute or judicial decision in most U.S. jurisdictions and in England. Its continued relevance is largely historical. Per diem damage arguments, by contrast, remain a live issue in civil litigation, with admissibility varying by jurisdiction.
Encyclopedia Cross-Reference
Damages and Remedies in Tort — Per Diem and Unit-of-Time Arguments for Pain and Suffering (The Law Mind Torts & Personal Injury Encyclopedia)