Google has added a few improvements to their Scholar search, one of which includes the ability to search for opinions from various federal and state courts.
Simple go to the Google Scholar Advanced Search page
Type in a keyword or phrase. — Remember, the more detailed the keyword is, the more accurate the search results will be.
Select “Legal Opinions and Journals” — This will result in results from both State and Federal courts.
Further refine the search by selecting either Federal courts, or courts from a specific state.
For a more advanced search:
Click “Select specific courts to search” for a complete list of the courts in the United States. This allows you to pick and choice between various states, Court of Appeals and the State Supreme Courts, as well as Federal courts.