Gaius Cassius Longinus was an Ancient Roman jurist and politician from the first century AD. A grandnephew of Servius Sulpicius Rufus, he was also a descendant, great grandson or nephew, of Gaius Cassius Longinus, one of Caesar's assassins.
Cassius, a pupil of Sabinus, was head of the legal school called the Sabinians or Cassinians. His principal works are the libri (commentarii) iuris civilis in at least ten volumes, which only survive in quotes by later authors such as Iavolenus. He held the offices of praetor, and of consul suffectus in 30, proconsul of Asia minor in 40–41, and legatus of Syria in 41-49. He was exiled by Nero to Sardinia in 65 and returned to Rome under Vespasian.
Tacitus includes a speech of Cassius on the debate that arose when there had been mass protests in Rome when 400 innocent slaves were to be executed because they belonged to the household of a master who had been murdered by his slave. It is open to question as the extent that the speech we have reflected what Cassius actually said and what extent it represents Tacitus's views though it is at least possible that Tacitus made use of the Senate's records and the hard line expressed is in line with what we know about Cassius. In the speech Cassius conceded that the execution would be unjust. He also conceded it violated the rights of private interests but justified it on the grounds of the public good. The private interests that concerned him did not include any right to life for the slaves but the loss to the heirs. Modern commentators side with those who protested at the time in regarding the law as inherently unjust.