"The charges Socrates faced seem ridiculous to us, but in Ancient Athens they were genuinely felt to serve the communal good."
Now that may well be true. I have no doubt that Professor's Cartledge's book-length study was assiduously researched and his conclusions are almost certainly stated in a sophisticated and nuanced way. All of this however is to miss the point. Socrates wanted to ask certain questions and did so. He persevered in asking them even when, or especially when they made people uncomfortable or even angry. In doing so he exercised a great deal of moral courage, in that he sought the truth even when he made enemies doing so.
Now we come to the point about legality. Professor Cartledge says that everything that the Athenian Court of the Archon did was lawful but here he is speaking as a good classicist and historian. (By the bye, I firmly believe that to be a good classicist and historian is no mean achievement and nothing I say here should be taken to denigrate those disciplines.) In other words he is prescinding from any moral judgement on what the court did in order to avoid, as a good historian should, falling into anachronism. What he fails to recognise on the Telegraph's admittedly journalistic reading of his work is that the law stands below moral judgement and is subject to it. At the very least, he fails to recognise that possibility.
I remember very clearly from my own brief and ignominious career as a classics and history student when a distinguished Classics lecturer made very similar point to the ones that Cartledge is now making. He pointed out that Socrates had broken the law of the day in that place and that he merited the punishment that the law enjoined. The philosophical-moral point of view is rather different, of course. If Socrates broke the law of the day then on Plato's account of his behaviour, that law required to be broken. No law is put in place ex nihilo. Even taking into account the law of unintended consequences, any new enactment embodies some social value or some desirable change. The process of practical reasoning about the social goods to be achieved precedes the drafting, passing and promulgation of a law.
Now a law can be debated in the appropriate forum, passed, enacted, handed down and enforced with both the appearance and the substance of lawful, constitutional order and still be wrong. By wrong, I mean unjust and morally repugnant. History is littered with examples of this. The loi de séparation of 1904, which effectively outlawed Catholicism in France has been gradually dismantled for this very reason. The apartheid regime of enforced racial segregation and subjugation in South Africa was likewise wholly lawful and constitutional but was still morally wrong. Likewise the infamous Dredd Scott decision of the United States Supreme Court can be seen now for what it is, a lawful act that was a perversion of justice.
As for what understanding of justice we must have to create a cogent critique of current legal norms, I suggest that we already have one. In fact, like any Natural Law moralist, I claim that this viewpoint is not merely prescriptive, telling us about what ought to be, but is also descriptive in that it tells us about what we already know to be true in the field of practical, moral reasoning.
I think Socrates' example is instructive and repays frequent re-reading; if you read those dialogues however, at some point, you have to suspend your historiographical suspension of judgement and decide who was more nearly right and who erred morally.