Copyright Alert System

Copyright Alert System (CAS) was a voluntary industry effort to educate and penalize internet users who engage in the unauthorized and unlawful distribution of copyrighted works via peer-to-peer file sharing services. The program was operated by the Center for Copyright Information, a consortium consisting of the Recording Industry Association of America (RIAA), the Motion Picture Association of America (MPAA), and the internet service providers AT&T, Cablevision, Comcast, Time Warner Cable, and Verizon.

The CAS used a graduated response system (also known as the "six strikes program"), in which participating ISPs would send warnings notifying subscribers of alleged copyright infringement, as reported by a monitoring service working on behalf of participating copyright owners. The system specified a six-step progression, from advice messages, to warnings that must be acknowledged by the user. After a fifth warning, ISPs were allowed to implement "mitigation measures", which could include penalties such as bandwidth throttling or preventing web access until customers "discuss the matter" with their ISP.

The CAS framework was established on July 7, 2011, after three years in the making. After multiple delays, ISPs began implementing it in late February 2013.

Due to the program not substantially decreasing piracy, the CAS discontinued the program on January 30, 2017.