In "The Stranger," how and why is Meursault condemned?

Meursault, after all, did kill another man.
His best defense would be that he acted in self-defense, but the text makes it sound like
deliberate and possibly premeditated murder. Camus was opposed to capital punishment, and his
novel seems intended more to show that capital punishment is absurd than that the legal system
is absurd. If he had written a story about an innocent man who gets sentenced to death through
circumstantial evidential or some other mistake, that would make us feel more sympathetic
towards Meursault. But it is clear that he didn't have to kill the Arab, and it is also clear
that he is lacking in normal human feelings for whatever reason. He not only seems indifferent
to killing another human being, but he seems indifferent to his own fate, thereby creating a bad
impression throughout his trial. The best that can be said for him is that he is honest. He
resembles Bartleby in Herman Melville's "Batleby the Scrivener."