The Official Google Blog describes an important new source:
As many of us recall from our civics lessons in school, the United States is a common law country. That means when judges issue opinions in legal cases, they often establish precedents that will guide the rulings of other judges in similar cases and jurisdictions. Over time, these legal opinions build, refine and clarify the laws that govern our land. For average citizens, however, it can be difficult to find or even read these landmark opinions. We think that’s a problem: Laws that you don’t know about, you can’t follow — or make effective arguments to change.
Starting today, we’re enabling people everywhere to find and read full text legal opinions from U.S. federal and state district, appellate and supreme courts using Google Scholar. You can find these opinions by searching for cases (like Planned Parenthood v. Casey), or by topics (like desegregation) or other queries that you are interested in.
Click the Official Google Blog link above to learn more. Attorneys must be used to this kind of access, but the cross referencing seems new to me. At least new to have it for free.