ISP Disconnects Internet With One Offense.

sandman83 writes: Yesterday evening my ISP "Cableone" disconnected my internet without any warning. I did managed to get it restored. They claimed that I downloaded a fansubbed anime called Queen's Blade (a one time offense) and that it's copyrighted in the US with no proof that it is. What I want to know is, is what they did completely legal within US laws, if it isn't? What do I need to do so this can be stopped?