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 belong 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 Senates 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.
Kupisch, Berthold (2001). "Cassius Longinus". In Michael Stolleis (ed.). Juristen: ein biographisches Lexikon; von der Antike bis zum 20. Jahrhundert (in German) (2nd ed.). München: Beck. p. 124. ISBN3-406-45957-9.