A more thorough explanation:

PRO SOCIO

Pro socio means "as a partner" in Latin. It refers to an action taken on behalf of a partner.

1. The company filed a lawsuit pro socio to protect the interests of its business partner.

2. The lawyer acted pro socio to defend the rights of their client's business partner.

Pro socio is used when one party takes action on behalf of another party who is their partner. In the examples given, the company and the lawyer are both acting pro socio to protect the interests and rights of their respective clients' partners. This term is often used in legal contexts to describe actions taken by lawyers or companies to defend the interests of their clients' partners.