Case law is always changing over time as other courts interpret and comment upon earlier decisions. One of the key steps in doing case law research is determining whether a particular case is still applicable to a certain situation.
Lexis Academic provides a way for researchers to check the status of a particular decision. After opening Lexis Academic, choose "US Legal" from the side menu, and then select "Shepard's Citations". With this tool, a researcher can enter a case citation and get a report that shows the history of that particular case as well as a list of other cases that discuss the citation entered.
Google Scholar also provides citation reports for the cases it covers.
The main database for researching state case law is Lexis Academic. After opening Lexis, choose "US Legal" from the side menu and then choose "Federal & State Cases".
On that page, you can choose the state you would like to search in by using the "jurisdiction" drop down menu.
Lexis Academic can be searched by citation, by party name, by legal topic, by judges, attorneys, or by keyword. You can also narrow the results by date.
Aside from Lexis Academic, there are other sources of state law available online:
Another important source for state case law is the websites of the state courts themselves. Often times the websites will have explanations of how a particular state's system works, links to case law available online, contact information, and other helpful resources for legal research.