Definition
Dies solis is a Latin phrase meaning "day of the sun," used in civil law and old English law to denote Sunday. The term appears in legal contexts primarily as a temporal designation — identifying Sunday as a day on which certain legal acts, court proceedings, or the running of legal time could be affected. In historical legal practice, Sunday carried special status as a dies non juridicus (a day on which courts did not sit and legal proceedings could not ordinarily be transacted), and dies solis served as the formal Latin label for that day within that framework.
Common Language
Modern common usage (Wiktionary): Not a standard entry in modern English dictionaries. "Dies" is occasionally recognized as a Latin root meaning "day," and "solis" as genitive of "sol" (sun), but the compound phrase has no entry in ordinary English usage.
Historical common usage (Webster's 1913): Not entered as an English term. Webster's 1913 recognizes "Sunday" as the first day of the week, set apart for rest and worship, but does not record the Latin designation.
The phrase has no meaningful life in common English. Its appearance in legal sources is purely technical, functioning as a formal Latin label carried over from Roman and early common law practice into legal instruments and treatises.
Why It Matters in Research
Dies solis is a navigational term rather than a substantive legal concept. Researchers encounter it almost exclusively in two contexts: (1) Latin-language passages in civil law sources and their English translations, and (2) older English legal treatises and forms discussing court days, process, and the computation of time.
The practical significance lies in its relationship to dies non. Because Sunday was historically treated as a dies non juridicus — a day on which legal proceedings were suspended and process could not be served or returned — identifying dies solis in a historical document may affect how a researcher interprets the computation of deadlines, the validity of service, or the enforceability of acts performed on that day. A deed executed, a writ returned, or a debt demanded on dies solis could raise questions of legal nullity in contexts governed by old English or civil law rules.
Researchers working with pre-modern English records should be aware that the day-of-the-week designations in Latin legal documents frequently use planetary names: dies Lunae (Monday), dies Martis (Tuesday), dies Mercurii (Wednesday), dies Jovis (Thursday), dies Veneris (Friday), dies Saturni (Saturday), and dies Solis (Sunday). Mistaking a day designation for a substantive legal term, or misreading the planetary genitive, can produce dating errors in document analysis.
The Justinianic citation in both Black's and Burrill's — Codex 3.12.7 — points to the Roman imperial prohibition on legal proceedings on Sunday, a provision that fed directly into canonical and later common law treatment of Sunday as a non-juridical day. Researchers tracing the history of Sunday-closing laws, Sabbath legislation, or the dies non doctrine will find dies solis a useful entry point into the civilian source tradition.
Historical Dictionary Support
Black's and Burrill's are in complete agreement: dies solis means Sunday, translated literally as "day of the sun," with both citing Codex 3.12.7 as the foundational civil law reference. Neither entry elaborates on the legal consequences attaching to dies solis beyond the bare identification of the day.
What the historical dictionaries omit is notable. Neither Black's nor Burrill's connects dies solis explicitly to the dies non juridicus doctrine, though that connection is the principal reason the term carries legal significance. The phrase functions in their entries as a simple glossary item — a Latin-to-English translation — rather than a gateway to the broader legal treatment of Sunday in both civil and common law systems. Researchers should not assume from the brevity of these entries that dies solis is legally inconsequential; the significance lies in what Sunday meant procedurally, not merely in what it was called.
Encyclopedia Cross-Reference
See Law Mind Encyclopedia: Dies Non Juridicus; Sunday Laws; Computation of Time (Legal)