Plenitudo Potestatis: Papal and Royal Fullness of Power in Hungary and the Holy See, 1100–1400

Plenitudo potestatis — the fullness of power — is medieval canon law's most charged legal phrase: not a declaration of supremacy but a jurisdictional switch that placed an act outside the reach of ordinary law, reserved to the pope or, in its royal adaptation, to the king. This study traces its intellectual genealogy and documentary history from 1100 to 1400. The concept descends from Roman imperial legal language (the emperor's legibus solutus and the lex regia), from the biblical commission to Peter (Matthew 16:18–19) and from Leo I's patristic formulation of the fullness against the delegated share; it was systematised by the Decretist glossators (Huguccio), amplified through Innocent III's decretal legislation (Per venerabilem, X 4.17.13), and refined by Innocent IV's Apparatus before Hostiensis forged its definitive canonical expression in the Summa Aurea (1253) and the Lectura (c.1262–71). Hostiensis extended the concept in two directions his predecessors had not taken: to the cardinals, through a collegial reading of 1 Corinthians 6:3 (iudicabitis in the plural), and to secular princes, who could act de plenitudine potestatis in their own sphere, with cause. The corpus documents the formula's subsequent spread using the archive of the Florilegium Reipublicae Christianae (charter corpus, snapshot of 12 November 2026): 319 records for the Kingdom of Hungary with Transylvania, 337 for the papal curia, and 238 for five comparison regions (Holy Roman Empire 202, France 15, England 26, Bohemia 3, Poland 1), drawn from twelve edited series. Across the Res Publica Christiana the formula moves primarily through the papal chancery and through canonist-trained court culture; the Empire mirrors Hungary's timeline, while France and England remain predominantly in the curial channel. In Hungary the curial peak in 1225–1274 — 170 records against only 33 from Hungary — reflects Hostiensis' active career; after 1300 the balance shifts: 59 Hungarian records in 1300–1324 against 89 curial, with Hungary first leading the curia in 1325–1349 (84 against 56), and 133 Hungarian records in 1375–1399 against only 8 curial. The Angevin bridge (Charles I, 1308–1342) is the most likely transmission channel; the explicit royal formula de Regie potestatis plenitudine (Louis I, 1352) is a deliberate transposition of the papal language to royal sovereignty. By Sigismund's reign (67 records in 1387–1399) the formula is a routine chancery clausula, present in voivoidal and sub-royal documents across Transylvania. This study is a corpus study: it counts and reads what a large body of edited medieval documents says about one concept, and sets that against modern scholarship. It was prepared with software and AI assistance. The counts, tables, charts and first draft were generated by a program (publisher.py) from the author's corpus, without a language model. The search rules, the concept's introductory paragraphs and the interpretive paragraphs were written with the help of an AI system (Claude, Anthropic), and a random sample of the matches was read in full to measure how many are true instances (section 2). The author read and approved the text before publication. Readings of the Latin marked as preliminary have not yet had a specialist's close reading. The counts depend on what the editions print and how their editors summarised it: editions are uneven by region and decade, modern summaries carry their editors' interpretations, and OCR may miss or misread words, so the numbers show proportions and trends, not totals. The study has not been peer reviewed. Corrections are welcome and will be published as new versions of this record.