Gottfrid Svartholm Warg, one of the defendants, argued the site was legal and that prosecutors would not succeed in shutting it down.
"What are they going to do about it?" he said, via a webcast news conference a day before the trial.
"They have already failed to take down the site once. Let them fail again."
John Kennedy, chairman of the International Federation of the Phonographic Industry, said the case was about protecting artists.
"The Pirate Bay has hurt creators of many different kinds of works, from music to film, from books to TV programmes," he said in a statement.
"It has been particularly harmful in distributing copyrighted works prior to their official release."
Despite several attempts by Swedish authorities and entertainment firms to close the website it is still online.
Representatives of the movie, music and video games industry are now asking for $11.9m in damages and interest for losses incurred from millions of illegal downloads facilitated by the website.
The case has been brought by entertainment firms including Warner Bros, Entertainment Inc, MGM Pictures, Colombia Pictures Industries, 20th Century Fox Films, Sony BMG, Universal and EMI.
Peter Sunde, another defendant, said that they had no grounds on which to demand damages, saying: "They won't get a cent."
The other two defendants are Fredrik Neij and Carl Lundstrom.
The case was opened in May, 2006, after police raided the website's locations in Sweden, seizing servers and computer equipment and temporarily shutting down the site.
If convicted, the defendants, who are formally charged with accessory and conspiracy to break Swedish copyright law, could face up to two years in prison.