Pro Socio Definition: Latin: on behalf of a partnership. To act for a partnership. A court application stated to be pro socio is made on behalf of a partnership. Used in Justinian's Institutes of 533 (III, xxv, 9) as follows: "It has been asked whether one partner is liable to another by the partnership action (pro socio) only for his fraud, like one who allows a thing to be deposited with him, or also for negligence, i.e. in respect of his inertia and lack of care: the view prevailed that he is liable also for negligence. But negligence, in this context, is not directed to the highest standard of care: it is enough that the partner shows, in partnership matters, such care as he would show in his own affairs. For one who takes a partner who is deficient in care, should complain of himself (i.e. attribute the defect to himself)." REFERENCES: Duhaime, Lloyd, Legal Definition of Partnership Categories & Topics: Company, Associations and Commercial Law Dictionary Dictionary of Latin Law Terms 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!