I've always thought of it in relation to the Materium, which has laws of physics and consistent patters of how time and matter relate to each other... until a writer needs a new plot tool, of course. I consider the Necrons to be one of the ultimate avatars of 'law', in the Michael Moorcock sense of law and chaos, in that they're immutable and follow these strictures even when not in their own best interest... possibly driven by their absolute lack of connection to the warp.
The Warp (powers), on the other hand, bends and turns back on itself in both form and function, and time and space... being bent to the will of whatever being has the greatest power to do so.
Also, keep in mind that the concepts of law and chaos were not meant to be mutually exclusive, but more of the yin and yang, constantly blending into each other despite their opposition.
The White Zone is for loading and unloading only. If you have to load, or if you have to unload, go to the White Zone. You'll love it... it's a way of life.
: Cigarettes in space?
: It's the final frontier, Nick.
: But wouldn't they blow up in an all oxygen environment?
: Probably. But it's an easy fix. One line of dialogue. 'Thank God we invented the... you know, whatever device.'