a contemporary of Cicero and of the scholars of Servius Sulpicius, was a pupil of Q. Cornelius Maximus (Cic. Fam. 7.8 and 17; and Dig. 33. tit. 7. s. 16.1.) Cicero recommended Testa to C. Julius Caesar (ad Fam. 7.5), during his proconsulship of Gallia, and in his letter to Caesar he spoke of him as an honest man, and as possessing a great knowledge of the Jus Civile. (As to the expression " familiam ducit" in Cicero's Letter to Caesar, see the note of Zimmern, p. 298, n. 7 : "quod familiam ducit," means " quod praecipuum est)." Trebatius had little taste for military matters, but still he kept with Caesar, and he wrote to Cicero and received from Cicero various letters while he was in Gaul (Cic. Ep. ad Fam. lib. vii.). It appears that Caesar offered him the pay of a tribune without requiring the discharge of the duties. and that Trebatius declined it. He did not accompany Caesar in his second British expedition, but he probably got a little inured to military service at last. Trebatius followed Caesar's party after the civil war broke out; and he wrote to Cicero to tell him that Caesar thought Cicero ought to join Caesar's side, or, if he would not do that, he ought to go to Greece and stay out of the way (Plutarch, Cicero, 100.37). Suetonius (Caesar, 100.78) tells an anecdote, that when all the senate approached Caesar, who was sitting in front of the temple of Venus Genetrix, with the decrees which conferred extraordinary honours on him, Trebatius advised Caesar to rise up to receive the senate, for which advice Caesar by his countenance showed his displeasure. Cicero dedicated to Trebatius his book of Topica, which he wrote to explain to him this book of Aristotle. The lawyer had turned it over in Cicero's library at Tusculum, but he found that it was too difficult for him (Topica, 100.1, ad Fam. 7.19), and he asked Cicero for an explanation. Trebatius enjoyed considerable reputation under Augustus as a lawyer, and he was one of those whom Augustus consulted as to the giving a legal effect to codicilli. Trebatius advised that these informal testamentary dispositions should be allowed to have legal effect : he said " that it was very useful and necessary for the Roman citizens that this should be so, on account of the long journeys which people often took, during which, if a man could not make his testament, he might yet make codicilli" (Inst. 2, tit. 25, De Codicillis). Horace addressed to Trebatius the first Satire of the Second Book.

Trebatius was the master of Labeo, who, however, aften differs from him in opinion (Dig. 16. tit. 3. s. 1.41; 18. tit. 6. s. 1.2). In the passage last referred to, the opinion of Labeo is decidedly right, and that of Trebatius as clearly wrong. He wrote some books (libri) De jure Civili, and nine books De Religionibus (Porphyrius, ad Horat. Sat. 2.1); but Macrobius (Macr. 3.3) quotes the tenth book Religionum. Trebatius is often cited in the Digest, but there is no direct excerpt from his writings. Pomponius speaks of several works of Trebatius being extant in his time, but he adds that his writings were not in great repute. His grammatical knowledge of his own language was ridiculously defective, for he said that Sacellum was composed of two words, sacrum and cella, a blunder which Gellius corrects (6.6).

The letters of Cicero to Trebatius are con tained among those ad Familiares (7.6-22). (Grotius, Vitae Jurisconsult. ; Zimmern, Geschieble, des Röm. Privatrechts, i. p. 297.)