Two days ago the Swedish police raided The Piratebays providers server park. Three Piratebay Admins were held in custody but were soon released. They are being charged with copyright infringement.
No crime has been proven yet, it’s still under investigation. This will probably the ultimate test to determine whether hosting a torrent tracker is illegal (in Sweden), or not.
The DOS attacks that took down the website of the Swedish police are likely to be the work of Piratebay sympathizers. A DOS attack (denial-of-service attack) is an attack on a computer system or network that causes a loss of service to users, typically the loss of network connectivity and services by consuming the bandwidth of the victim network or overloading the computational resources of the victim system.