These sources contain background information on research topics. Some can be used to collect data. Others allow for direct data export.

Global High Court Websites
Justia, U.S. Supreme Court Opinions
Legal Information Institute
Oyez, U.S. Supreme Court Oral Arguments
Public Access to Court Electronic Records (PACER)
National Center for State Courts
Federal Judicial Center
National Archive of Criminal Justice Data
FBI Uniform Crime Reporting Statistics
Bureau of Justice Statistics Datasets