Google’s new News Archive Search is an amazing tool that lets you search 200 years worth of news articles. It includes both free and fee-based content from news organizations including Time, The Wall Street Journal, The New York Times, the Washington Post and many others. For a full review, see Google Debuts 200 Year News Archive Search.
Not immediately obvious to the new user is that the news archive includes historical caselaw from various sources. A search of my own name brought up these cases from the 1980s. One, an appeal to the 3rd U.S. Circuit Court of Appeals, is available via Google from VersusLaw, Fastcase and Loislaw. All charge a fee for access to the full decision — $2.95 on VersusLaw, $4.99 on Fastcase and $24.99 on Loislaw (for a 24-hour pass). The other case that came up is a U.S. District Court opinion from the Virgin Islands available only on VersusLaw.
I could find no information on Google about the depth of availability of court opinions. But when searching for older caselaw, keep this in mind as a source.