VI.8 On accusations under the various governments
In Rome  one citizen was allowed to accuse another ; this was established in the spirit of the republic, where every citizen must have unlimited zeal for the public welfare, and where every citizen is supposed to hold all the rights of the homeland in his hands. Under the emperors they followed the maxims of the republic, and right away they saw the appearance of a deadly kind of men : a band of informers. Anyone who had many vices and many talents, a thoroughly base soul, and an ambitious spirit, looked for a criminal whose condemnation could please the prince : this was the path to honors and fortune,  something we never see in our country.
Today we have an admirable law, which would have the prince who is established to have the laws executed appoint an officer in each tribunal to prosecute all crimes in his name ; as a result, the function of informer is unknown here ; and if that public avenger were suspected of abusing his ministry, he would be forced to name his informer.
In Plato’s Laws,  those who fail to notify the magistrates, or to lend them aid, are to be punished. Today that would not be appropriate. The public sector keeps watch for the citizens ; it acts, and they are tranquil.