This proves, to his satisfaction, that people act justly only under compulsion. Now the shepherds met together, according to custom, that they might send their monthly report about the flocks to the king; into their assembly he came having the ring on his finger, and as he was sitting among them he chanced to turn the collet of the ring inside his hand, when instantly he became invisible to the rest of the company and they began to speak of him as if he were no longer present.
He acted violently on the power gained from the ring.
Glaucon posits: Suppose now that there were two such magic rings, and the just put on one of them and the unjust the other; no man can be imagined to be of such an iron nature that he would stand fast in justice. Glaucon begins by asserting that people find it desirable or good to inflict wrongdoings on others but these wrongdoers regarded being on the receiving end of misdeeds as undesirable.
And for that reason, we cannot outlaw anonymity because it is merely a blanket solution to a deeper and more complex issue. The story he tells acts as a thought-experiment.
I believe that it does not take anonymity to be unjust. If you could imagine any one obtaining this power of becoming invisible, and never doing any wrong or touching what was another's, he would be thought by the lookers-on to be a most wretched idiot, although they would praise him to one another's faces, and keep up appearances with one another from a fear that they too might suffer injustice.
If Plato's allegory of the ring is right, then we had better watch out. As people grow more and more confident in their ability to speak out and act upon hatred, there will be more confidence in sharing things publicly.