Google has announced that it has changed how it displays citations to legal opinions:
Now, instead of sorting the citing documents by their prominence, we sort them by the extent of discussion of the cited case. Opinions that discuss the cited case in detail are presented before ones that mention the case briefly. We indicate the extent of discussion visually and indicate opinions that discuss the cited case at length, that discuss it moderately and those that discuss it briefly. Opinions that don’t discuss the cited case are left unmarked.