I think they are referred to as "Detailed Law Levels", rather than "Sub-Law Levels", but that's a minor quibble. ;-)
The first check regarding "Law-Related Details" is for uniformity of law: does the Law Level apply to the entire planet? (c.v. "Rescue on Ruie", JTAS 1).
The second is to flesh out the Law Profile, where the simple (simplistic? ;-) ) Law Level is broken down into the following "Detailed Law Levels":
Overall - Weapons | Trade | Criminal Law | Civil Law | Personal Freedom
e.g. 9-B76AA
(all WBH, p 82)
Then the referee applies their understanding of the basic Law Level rules to each component, when necessary. Law Level is defined as " The degree to which the law interferes with individual actions" (WBH, p 57).
And the WBH also says, "It is more difficult to make precise rules for law levels than for government types. the law related details given on the charts are largely suggestions -- you as referee must rely on your sense of the game to temper any law-related details." (ibid)
IOW, you can use the law level breakdowns as target numbers to roll against whenever you think the PCs are doing something you don't want them to do, or you want to chuck in some "heat" to keep them honest.
Law Level, therefore, is tempered by the speed of plot.