The Center for Computer-Assisted Legal Instruction (CALI)'s Free Law Reporter (FLR) is an electronic case reporter that freely publishes nearly every recent appellate and supreme court opinion, from state to federal U.S. courts.
This project builds upon Carl Malamud's Report of Current Opinions (RECOP) and, hence, contains whatever is included in the slip opinion archives of the RECOP. This includes primarily appellate level courts in the 50 states and D.C., the federal courts and SCOTUS. For the most part, coverage begins with 1/1/2011 and continues forward.
Below are sites that also provide access to California case law:
The availability of state court documents online varies widely by court. Please see the article by Rachel Samberg linked below for further information on this topic.
You may have to register and pay for online access; for example, the Los Angeles Superior Court has an online system but requires registration and payment for searches and downloaded documents. See link below.