When Tarrou describes the big courtroom scene of his youth, he repeatedly refers to the red robes that his father, the prosecutor, wears while condemning a man to death. Besides the trite and obvious red = blood stuff, which we’re not even going to talk about, think about the notion of putting on clothes – like robes, to pull an example out of a hat – and what that signifies. It’s a process of covering up and of assuming a certain identity. Here we go again with Kierkegaardian roles (see Cottard’s "Character Analysis" for all the gory detail). Tarrou’s father is able to condemn men to death because that is simply his job. (Interesting, since Rieux uses the same reasoning to justify turning his back on his wife. Moral relativism yet again, but that’s another story.) Tarrou’s father assumes the role of prosecutor and all that goes with it by physically changing his outward appearance – by putting on the red robes.