We are taught much less about the classics than we once were, so the name of Rhadamanthus (sometimes spelt Rhadamanthys) probably rings few bells.
In Greek mythology, he was the son of Zeus and Europa, brother to King Minos of Crete and (in some versions of the tale), Prince Sarpedon of Lycia. In life he was renowned for his wisdom and justice. When he died, according to Plato, he went to Elysium, where the most favoured mortals were chosen by the gods to stay eternally, and there became ruler and judge. Together with Minos and Aeacus, he decided the fate of everyone who was brought before him — whether to live forever in Elysium, or be banished to the underworld — and in judging was able to detect all the sins of one’s life, no matter how well hidden.
So Rhadamanthus became a byword for justice in its most severe and rigorous form and the adjective rhadamanthine refers to a person who is rigorously just and severe. It appeared in English near the end of the eighteenth century. An example of its use is in The Egoist by George Meredith: “As to the sentence he pronounces, I am unable to speak, but his forehead is Rhadamanthine condemnation”. A recent use:
In a Rhadamanthine judgment on 11 April 2000, Mr Justice Charles Gray ruled that Irving was an anti-Semite and pro-Nazi who deliberately falsified and distorted the historical record of the Third Reich in the service of his ideology.
New Statesman, 26 Mar. 2001.