PRISM refers to an NSA operation begun in 2007 to collect private information from large US internet sites such as those operated by Microsoft, Google, and Yahoo. Its existence was revealed in 2013 by Edward Snowden,
UK use of PRISM data
Allegations that GCHQ illegally obtained data via PRISM were investigated by the Intelligence and Security Committee. The committee did not find evidence that data was obtained outside of UK legislation, such as warrants issued under the Regulation of Investigatory Powers Act 2000.
European Parliament inquiry
In July 2013 the European Parliament voted to launch in-depth inquiry into US surveillance programmes. Claude Moraes MEP has been appointed Rapporteur for the Committee on Civil Liberties, Justice and Home Affairs inquiry.