There are many different criteria for ranking law schools:
In looking at law schools, you should be very careful to note the criteria used, the methodology used, and the identity and motivations of the ranking entity.
A word on "academic quality" rankings: keep in mind that except for the very top 10 or 20 law schools and the very bottom 10 or 20, there really are not significant differences among those many law schools in the crowded middle. Trying to distinguish among them is a little like trying to rank in order of height the many blades of grass in a field. They can be ranked, but the ranking does not provide meaningful distinctions, except to point out the giants and the runts.