The collection of legal materials accessible via the Internet is growing at a fast clip. But the decision whether to place particular court's decisions on the Net and how is a local one. The same holds for agency documents of all kinds (exept for regulations compiled into the Code of Federal Regulations).
Even as to courts and agencies that have moved large collections of legal materials to the Net, the recency of that action affects the depth of available information. This is particularly true of judicial opinions. With few exceptions collections of judicial opinions accessible through these pages cover only the most recent years.
Thorough research on many legal matters calls for exploring not only Federal but state law. If you are uncertain about the mix of Federal and state law in a particular area or seek references to the relevant state materials you may wish to consult the LII "Law About ..." pages. Alternatively, you may wish to go straight to the LII State Law Collection following your investigation of Federal law on the topic.