Take a look at the Federal court system
The authorised report series for the US Supreme Court is the United States Reports (US)
Legal Opinions via Google Scholar (also provides citing information)
Early American Case Law (Hein Online) - Contains the entire Federal Cases 30 book series (1894-1897) which contains more than 20,000 cases. Also included is the Trinity Series, which includes American Decisions, American Reports, and American State Reports.
State Reports: an Historical Archive (Hein Online) provides a digital version of Heins State Reports Checklist along with linking to the full text of historical state reports.
Use Ravel.com's visual representation tool to map and understand the relationships between cases.
The United States Code (USC) and Public Laws are freely available online via:
and via Hein Online.
State codes are available via Cornell Law School's, LII.
Historical versions are on Hein Online State Statutes: A Historical Archive