A member of the noble family of the Ubaldi (Baldeschi), Baldus was born at Perugia in 1327, and studied civil law there under Bartolus de Saxoferrato, being admitted to the degree of doctor of civil law at the early age of seventeen. Federicus Petrucius of Siena is said to have been the master under whom he studied canon law.
On his promotion to the doctorate he went to Bologna, where he taught law for three years, after which he was advanced to a professorship at Perugia, where he remained for thirty-three years, and he had among his students Francesco Albergotti. He subsequently taught law at Pisa, Florence, Padua and Pavia, the rivals to Bologna. During his period at Pavia he sometimes also taught at Piacenza. He died at Pavia on 28 April 1400 and was buried in the church of San Francesco.
Baldus was the master of Pierre Roger de Beaufort, who became pope under the title of Gregory XI, and whose immediate successor, Urban VI, summoned Baldus to Rome to assist him by his consultations in 1380 against the anti-pope Clement VII. Baldus' view on the legal issues relating to the schism are laid down in the so-called Questio de schismate. Cardinal Francesco Zabarella and Paulus Castrensis were also among his pupils.
Many of Baldus' works are incomplete. He left voluminous commentaries on the Pandects and on the Codex Justinianus. His Commentary on the Libri Feudorum, a twelfth-century compilation of feudal law provisions, is considered to be one of his best works. He also commented on the canon law compilations of decretals, the Liber Extra and the Liber Sextus. In addition to these commentaries, Baldus wrote a number of treatises on specialised legal topics. His major effort, however, went into the writing of some 3,000 consilia (legal opinions). No other medieval lawyer has so many consilia preserved.
Baldus's work on the law of evidence and the gradations of proof was a high point of medieval thought in the discipline and remained the standard treatment of the subject for centuries.
- De syndicatu officialium
- De duobus fratribus
- De significatione verborum
- De pace Constantiae
- De feudis
- Summula respiciens facta mercatorum.
- Commentaria in digestum vetus, 1549.
- Consiliorum sive responsorum, 1575.
- In usus feudorum commentaria (in Latin). 1580.
Baldus had two brothers, Angelus (1328–1400) and Petrus (1335–1400). It is probably due to confusion between Baldus and his brother Petrus that the famous jurist's name is sometimes given as Petrus Baldus de Ubaldis.
- "ALBERGOTTI, Francesco in "Enciclopedia Italiana"". www.treccani.it (in Italian). Retrieved 2021-03-08.
- Pennington, Kenneth (1997). "Baldus de Ubaldis". Rivista internazionale di diritto comune. 8: 35. Retrieved 30 June 2021.
- "Lapide di Baldo degli Ubaldi". Pellegrini del Sapere. Retrieved 2 August 2022.
- Franklin, James (2001). The Science of Conjecture: Evidence and Probability Before Pascal. Baltimore: Johns Hopkins University Press. pp. 30–33, 43–45. ISBN 0-8018-6569-7.
- Chisholm, Hugh, ed. (1911). Encyclopædia Britannica (11th ed.). Cambridge University Press. .
- J. Canning, The Political Thought of Baldus de Ubaldis (Cambridge University Press, 1987)
- J. Franklin, The Science of Conjecture: Evidence and Probability Before Pascal (Johns Hopkins University Press, 2001) ch. 2
- "VI Centenario della morte di Baldo degli Ubaldi," "Ius commune," 27 (2000).
- "VI Centenario della morte di Baldo degli Ubaldi 1400-2000," eds. Carla Frova, Maria Grazia Nico Ottaviani, and Stefania Zucchini (Perugia: Università degli Studi, 2005).
- G. Hamza, "Entstehung und Entwicklung der modernen Privatrechtsordnungen und die römischrechtliche Tradition" (Eotvos Universitätsverlag, Budapest, 2009) p. 78-89.
- G. Hamza, "Origine e sviluppo degli ordinamenti giusprivatistici moderni in base alla tradizione del diritto romano" (Andavira Editora, Santiago de Compostela, 2013) p. 79-86.
- Treggiari, Ferdinando (2020). "UBALDI, Baldo degli". Dizionario Biografico degli Italiani, Volume 97: Trivulzio–Valeri (in Italian). Rome: Istituto dell'Enciclopedia Italiana. ISBN 978-8-81200032-6.
- Biography by Ken Pennington at Catholic University of America
- Baldus de Ubaldis in the German National Library catalogue
- Daniel Schwenzer, "Baldus de Ubaldis". Biographisch-Bibliographisches Kirchenlexikon (BBKL) (in German).
- Guide to Baldo degli Ubaldi, Consilia de Iure. Manuscript, circa 1420 at the University of Chicago Special Collections
- Complete works and editions by Baldus de Ubaldis at ParalipomenaIuris