Does anyone know of an article outlining the laws of the Emperor or of the Old World in general? I know that it's far more complex than in modern times, since smaller villages, etc., may have their own informal legal codes, but is there something that outlines the overarching ideals?

This was touched lightly in 2nd ed but never in depth. What they did print was in the WFRP Companion and SIgmar's Heirs and is entertaining to read. The Companion has a system for adjudication, but not much in the way of actual laws. As far as I've seen its just suggested to make stuff up on the fly, and plenty of common-sense laws are in effect.

Just remember that in Old World you are guilty until you can prove you are innocent :-)

I like the look on the faces of any new player when he hears that line from any official after being charged with murder ;-)