Bonus pater familias Definition: Latin: the good family man. Related Terms: Reasonable Man The ordinary prudent person. The legal fiction of a ethereal reference point against which to judge the conduct of those against which an allegation of negligence lies. In Roman law, as in the subsequent civil law which has superceded it, civil liability is often determined against the standard of the civil law 's equivalent to the common law's reasonable man: the bonus paper familias. In French-speaking jurisdictions, all civil law lawyers will recognize the term bon pere de famille as readily as a common law lawyer would recognize the term reasonable man. Some have described the concept of the ideal, the bonus pater familias as simply an appeal to local custom in any given situation.1 REFERENCES: Bouchard c. Courcy, 2010 QCCS 2285, ¶40 Duhaime, Lloyd, The Reasonable Man: Law's Ghost God Jorgensen, Stig, Liability and Fault, 49 Tul. L. Rev. 329 (1974-1975 - NOTE 1) Mayrand, Albert, Dictionnaire de maximes et locutions latines utilisées en droit (Montréal: Éditions Yvon Blais, 2007), page 60 Categories & Topics: Civil Law Dictionary Dictionary of Latin Law Terms Tort and Personal Injury Law Dictionary Find you are constantly looking up definitions? Try our search provider (works in most modern browsers) If you find an error or omission in Duhaime's Legal Dictionary, or if you have legal term suggestion, we'd love to hear from you!