The same day a new antipiracy law went into effect in Sweden, Internet traffic took a dive and five audio book publishers went after an alleged illegal file sharer in court. The so-called IPRED law, which went into effect Wednesday, requires Internet service providers to reveal subscribers' Internet Protocol addresses to copyright holders in cases where a court finds ample evidence of illegal activity. As of 2 p.m. local time Wednesday in Sweden, Internet traffic was down about 30 percent from the day before, according to Computer Sweden (in Swedish). Also on Wednesday, Earbooks, Storyside, Piratforlaget, Bonniers, and Norstedts took advantage of the legislation, bringing their grievances to a district court in the Stockholm suburb of Solna in an attempt to reveal the identity of the person behind a particular IP address. Among the authors with works published by those companies are noted crime novelists Henning Mankell, Hakan Nesser, and the estate of deceased crime novelist Stieg Larsson. The Swedish Publishers' Association, which supports the audio book publishers' action, claims the alleged pirate had up to 2,000 audio books stored on a server. The illegal file sharing of audio books has increased over the past year, according to the organization. The case will likely serve as precedent; the record industry confirmed Wednesday that it is preparing its own first case. An estimated 1 in 10 people engage in file sharing in Sweden. The country is also home to the world's largest BitTorrent sharing site, The Pirate Bay.