Ha! That's one of the versions I have as well, if it's the one I think he means. It was part of the boxed set that came out in the mid-80's, with Character Law/Campaign law in one volume, Arms law/Claw Law (on light card stock) in a second, and Spell Law in the third. IIRC, the original cover was a bluish color. My cover has long since fallen away, but I refuse to give up my book.
But, that's RM2, right? The one where the chanelling, essence, and mentalism pamphlet-type books were separated into individual realms was the original RM1, correct? When the material was revised for a unified system (somewhat) rather than as simply supplements to other games, that's when it became RM2 as I understand the breakdown.