The "six-strike" warning system that aims to curb illegal downloads in the U.S. is set to go live today after missing its scheduled launch in November. AT&T, Cablevision, Verizon, Time Warner Cable, and Comcast are all on board with the so-called Copyright Alert System, under which copyright offenders will receive a series of escalating warnings and can ultimately result in "mitigation measures" being taken against them.
The emphasis is reportedly on education, and despite some concerns, it doesn't seem like ISPs will be watching their customers' traffic. Instead, it's up to content owners to monitor peer-to-peer networks and notify service providers whenever their customers are suspected of trading copyrighted files online. From there it's up to the service providers to get in touch with those users.
The specific alerts issued by ISPs will vary from one to the other but they more or less follow the same guidelines with three tiers of warnings and two warnings per tier. The first two notifications are expected to serve as warnings, alerting users of the offense and pointing them to legitimate sources of content. The second two are "acknowledgement alerts" requiring users to confirm receipt of the message before they can start browsing again, while the last two can include things like temporary bandwidth throttling, blocking access to certain websites, or warning about potential legal action from the content owner.
At least on paper, the measures are not as severe as previous attempts to counter piracy, both in the U.S. and elsewhere. But they are nonetheless the result of unverified accusations by private entities, not something that has gone through a judge. There's not much stopping content owners from accusing you with little or unreliable proof, making ISPs slap you with whatever alert tier is up. You can still appeal if you feel wrongly accused but it'll cost you $35 for an independent review by the American Arbitration Association.
It's worth noting that the copyright alerts only appear target a subgroup of users, namely those sharing through BitTorrent. According to TorrentFreak, "the millions of users of file-hosting services, Usenet and streaming sites are not going to be affected." The site goes on to point out that even those who keep using BitTorrent can avoid the warnings by signing up for one of many anonymizing services like proxies and VPNs.