Javert passed slowly down the Rue de l’Homme Armé.
He walked with drooping head for the first time in his life, and likewise, for the first time in his life, with his hands behind his back.
Up to that day, Javert had borrowed from Napoleon’s attitudes, only that which is expressive of resolution, with arms folded across the chest; that which is expressive of uncertainty—with the hands behind the back—had been unknown to him.
Why don’t the illustrators pay attention?
Edit: I agree that folding your arms across your chest doesn’t necessarily express resolution, and clasping your hands behind your back doesn’t necessarily express uncertainty. But my point is that Hugo has specifically said that Javert never does that one thing, and then the illustrators have to go and draw him doing it (and usually in his introductory illustration, no less).