Definition
Latin: "for the thing born," rendered in legal usage as "for the immediate occasion" or "for the affair immediately at hand." The phrase describes action taken in response to a specific exigency or pressing circumstance rather than in conformity with established procedure, rule, or precedent. In legal and parliamentary contexts, something done pro re nata is adapted to meet a particular situation as it arises — improvised, in a sense, by necessity — rather than flowing from ordinary course.
The phrase appears most often in two distinct contexts:
1. JUDICIAL OR PROCEDURAL USE: A court or deliberative body acting pro re nata departs from ordinary procedure or established practice because the immediate circumstances demand it. The action is legitimate but exceptional — shaped by the exigency of the moment rather than by settled rule.
2. LEGISLATIVE OR ASSEMBLY USE: A meeting or session convened pro re nata is one called for a specific, immediate purpose rather than as a regularly scheduled proceeding. Historically this usage appeared in accounts of ecclesiastical and parliamentary bodies convening under special or urgent circumstances.
---
Common Language
Modern common usage (Wiktionary): In contemporary general usage, pro re nata is most familiar from medical and pharmaceutical contexts, where it is abbreviated PRN on prescriptions and medical charts to indicate that a medication or treatment should be administered as needed, at the discretion of nursing staff or the patient, rather than on a fixed schedule.
Historical common usage: The phrase does not appear in Webster's 1913 as a standard English entry, reflecting its status as learned Latin retained in specialist vocabulary rather than absorbed into common English.
Editorial note: The legal meaning and the medical meaning share a structural logic — both describe action calibrated to circumstances as they arise rather than by fixed routine — but the applications diverge sharply. A researcher encountering PRN in a legal document should not read it through the medical lens, and vice versa. In legal sources, pro re nata signals exceptional procedure or emergency action, carrying an implicit acknowledgment that normal rules are being set aside; in medical usage, it is simply a routine dosing instruction.
---
Common Confusion
Pro re nata is occasionally conflated with pro hac vice ("for this occasion only"), and the two phrases do overlap conceptually. Both describe action taken outside ordinary course. The distinction matters: pro hac vice typically attaches to a specific permission granted for one occasion (most commonly, attorney admission to appear before a court), while pro re nata describes the character of the action itself — that it is improvised or adapted to meet an immediate exigency, without necessarily implying a formal grant of permission. A judicial ruling may be pro re nata without anyone having sought or received pro hac vice status, and pro hac vice admission does not make the underlying proceedings pro re nata.
---
Why It Matters in Research
Researchers in the Law Mind corpus will encounter pro re nata primarily in older judicial opinions, ecclesiastical law materials, parliamentary records, and early American legal commentary. Several navigational points are worth flagging:
First, the phrase signals a moment of procedural improvisation. When a court or writer describes an action as pro re nata, it is often acknowledging that normal rules were not followed — which may be legally significant. In historical sources, this usage frequently surfaces in discussions of equity jurisdiction, prerogative courts, or emergency legislative sessions, where the justification for irregular action was precisely the pressing nature of the circumstances.
Second, Burrill cites Blackstone's Commentaries for the phrase, pointing to its appearance in foundational English legal exposition. Researchers tracing a historical argument about emergency judicial power or exceptional procedure will want to check those Blackstone references alongside whatever primary source they are reading.
Third, the abbreviation PRN in any document produced after roughly the mid-twentieth century almost certainly carries medical rather than legal meaning. In older documents — particularly handwritten legal records, ecclesiastical minutes, or colonial-era materials — the same abbreviation or its spelled-out form likely carries the legal or procedural meaning. Context is everything.
Fourth, researchers should be alert to the phrase in accounts of meetings or assemblies. A session convened pro re nata is not a regular meeting, and its acts may have different procedural standing or validity than acts of a regularly constituted assembly.
---
Historical Dictionary Support
The four historical sources agree on the core meaning but vary in emphasis. Black's second edition offers the most developed gloss — "adapted to meet the particular occasion" — and supplies a concrete example of judicial action taken under pressure of exigency rather than in conformity with precedent. This is the most practically useful historical formulation. The first edition of Black's appears to have been truncated in the available text.
Rapalje and Lawrence reduce the phrase to its functional essence: "to meet the emergency." This compression is accurate but loses the nuance that pro re nata action need not always rise to the level of emergency — unusual circumstances or pressing occasion suffice.
Burrill, characteristically, anchors the phrase in Blackstone and keeps the definition spare: "for the immediate occasion." His Blackstone references (1 Bl. Com. 174; 3 Id. 73, 433) are worth consulting by any researcher who needs to trace how the concept functioned in English common law thinking.
None of the historical dictionaries address the medical usage, which had not yet become dominant in general vocabulary at the time these works were compiled. This gap means historical legal dictionaries are reliable guides to the legal meaning but cannot help researchers navigate the modern ambiguity between legal and medical contexts.
---