The Copyright Alert System went into effect Monday February 25th, 2013. The Copyright Alert System is an effort by copyright holders, mainly the Recording Industry Association of America (RIAA) and the Motion Picture Association Of America (MPAA) to curb copyright infringement. It is NOT a law, but an avenue for copyright holders to contact offending parties via their ISP.
It works as follows:
Copyright holders will monitor (they are already and have been doing this for a long time already) Peer-2-Peer networks for copyright infringements and identify the IP address of the infringing party. They will then provide this information to the Internet Service Provider (ISP) owning that IP address. The ISP will then identify the user who used that particular IP address at the time of the alleged violation and notify the user of the complaint. There are several levels of alerts to the user ranging from an informative emails to mandatory educational videos and upon further violations bandwidth throttling.
What does that mean to you?
Frankly, very little. In contrast to similar systems in other countries there won't be any service suspensions or fines, merely annoyances for serial offenders. ISPs will not share subscriber information with copyright holders and copyright holders can still sue users independent of CAS.
What can you do to protect yourself?
While much is being written about CAS, I am not sure what it will accomplish. If you are concerned about it, your best bet is to use a no-log VPN whenever your are online, thereby making it impossible for others to determine your real identity. For more, read "Why Use No Log VPN".
CAS is another effort to maintain outdated business models rather than engaging in meaningful discussions about copyright and patent law. In my opinion CAS is more geared towards publicity than copyright protection. If you are concerned about CAS, protect your privacy using a VPN, logging or no-log VPN, and you have little to worry about.
Resources: Cute Copyright Alert System Video
Image Credit: Retromodern