Client (Lat. cliens, according to some from an old Latin verb, cluere, to obey), in Roman antiquity, a man of inferior class, or lower situation, connected for mutual service and obligation with a citizen of better standing, in this relation called patron (patronus), or protector. This relation of client and patron (clientela), which seems to have been of great historical importance in the first centuries of the Roman state, is said to have been introduced by Romulus, in order to form a social link connecting the two separate and naturally antagonistic bodies of Roman society, the patricians and the plebeians. Some even believe that at the earliest period of Roman history the names patricians and patrons were identical, and that the clients embraced the whole bulk of the plebs. But this supposition, though founded on testimony of ancient date, can hardly be proved, the history of this institution in general being involved in great obscurity. According to Diony-sins, whose history contains a summary of the mutual obligations of clients and patrons, together with a historical sketch of the institution, both of doubtful accuracy, the patron was the legal adviser and paternal protector of the client, and bound to assist him in need or danger; the client was bound to filial respect and reciprocal assistance, to contribute to the portion of the patron's daughters in case he became poor, to ransom him if made captive, and to vote for him or his friends when standing for office.
The client and patron were not allowed to sue or to bear witness against each other, and had religiously to abstain from any injury to each other. The client accompanied his patron in war, being in this respect similar to the vassal of the middle ages, and bore his family name, partaking in the sacrifices and sepulchre of the gens with which he was thus associated. If he died without an heir, his patron (according to Kiebuhr) inherited his property. The wife of the latter was the matron a or patroness of the protected family. Illustrious families found their pride in the number of their clients, and strove to gain new ones, the relation being hereditary. Freedmen became natural clients. It is stated that Romulus, regarding the connection as a religious tie, and an infringement upon its duties as a sacrilegious act, bestowed upon clients the right of unlimited self-defence against tyrannical patrons, but this can hardly be accepted. Whatever the original condition of the clients may have been, their situation was made more favorable by the constitution of Servius Tullius, admitting the plebeians to a regular share in the political affairs of the state. Though greatly modified in the course of time, the institution maintained itself down to the period of the emperors.
Foreigners also often stood under the protection of distinguished Roman citizens, chosen as patrons. Even foreign states which were in alliance with Rome had their patrons in the capital of the mighty republic, and the senate often referred the decision of international disputes to the respective patrons. Similar institutions are said to have existed at an early age among other nations of Italy, as well as among some tribes of Thessaly. - In modern usage the term client designates a person who commits his legal cause to a lawyer or counsellor.