(a) The law of the Twelve Tables (451 B.C.) ordained, with respect to jurisdiction, “de capite civis nisi per maximum comitiatum ... ne ferunto” (Cic. de Leg. iii. 4, 11). The mention of the “greatest comitia” clearly implies the existence of a lesser one with judicial powers; and as this is not likely to have been the comitia curiata of the period, it can hardly be any other assembly than the comitia of the tribes.
(b) The quaestors were first elected by the people in 447 B.C. (Tac. Ann. xi 22), and in later times their appointment was made by a comitia of the tribes (Cic. ad Fam. vii 30).
(c) The first legislative act of the people gathered tributim is attributed to the year 357 B.C. (Liv. vii. 16 (consul) “legem novo exemplo ad Sutrium in castris tributim de vicensima eorum, qui manu mitterentur, tulit”).
The comitia tributa populi was probably created between 471 B.C., the date at which the Plebs began to meet tributim, and 451, the date at which the existence of such an assembly is hinted at in the Twelve Tables.
(iii.) In the developed Republic we find an assembly meeting by tribes—
(a) which is presided over by magistrates of the people, e.g. by the consuls Manlius (Liv. vii. 16) and T. Quinctius Crispinus (Frontinus de Aquaed. 129), by the dictator Caesar (Cic. ad Fam. vii. 30), and by P. Clodius as curule aedile (Cic. pro Sest. 44, 95; ad Q. fr. 2, 3);
(b) which elects magistrates of the people, e.g. the quaestors (Cic. ad Fam. vii. 30 “comitiis quaestoriis institutis ... ille (Caesar) ... qui comitiis tributis esset auspicatus”) and the curule aediles (Gell. vii. 9 “[Cn. Flavium] pro tribu aedilem curulem renuntiaverunt”);
(c) which legislates. This legislative power is shown by the lex Quinctia de aquaeductibus of 9 B.C. (Frontinus de Aquaed. 129);
(d) and exercises judicial power. This judicial power is shown in the trial of Milo for vis in 56 B.C. (Cic. pro Sest. 44, 95; ad Q. fr. 2, 3). The prosecutor was a curule aedile, and the trial took place in the Forum (“ejectus de rostris Clodius,” l.c. § 2).
Perhaps the most striking demonstration of the existence of this assembly is contained in the prescription to the lex Quinctia de aquaeductibus (Frontinus l.c.), which runs as follows:—