Roswall argued that The Pirate Bay was far more than the “hobby site” claimed by the four men accused in the case, estimating that the site generated net profits of around 10 million kronor ($1.1 million) a year.
The indictment concerns 33 works, including albums, films, and computer games, which together were downloaded a total of 435,000 times, according to the prosecutor.
Roswall pointed out that the standard for demonstrating complicity in a crime in Sweden is relatively low and used assault as a comparison.
“A person who is holding someone's coat while they assault someone else is complicit in the crime,” he told the Stockholm court.
Roswall rejected as “a technical objection” arguments by the defence that file sharers may have located torrent files using torrent trackers other than those from The Pirate Bay.
What's important, he argued, is that The Pirate Bay's trackers can be used.
While Roswall admitted that the EU directive on e-commerce which protects operators of web-based businesses from responsibility for the information transferred through their websites does apply to The Pirate Bay, he didn't think a ruling from the European Court of Justice was required to determine precisely how the directive applied.
“It doesn't mean some sort of immunity for middlemen. And there is no reason to request an opinion from the European Court,” he argued.
In the indictment, prosecutors estimated that The Pirate Bay earned about 1.2 million kronor per year.
“But my estimate is extremely low. The profits are much greater than that,” Roswall said on Monday, after which he cited new calculations showing that The Pirate Bay generates annual income of 11.6 million kronor.
After deducting expenses, The Pirate Bay's yearly profit comes to around 10 million kronor, according to Roswall.
“And therefore The Pirate Bay isn't some sort of charity operation. It's a business,” he said.
Speaking during a break in the trial, Svartholm Warg, cast doubt on Roswall's numbers.
“It's totally absurd, those numbers are totally disconnected from reality,” he told the TT news agency.
Nevertheless, Svartholm Warg was surprised that prosecutors were only seeking a sentence of one year in prison.
“I was actually surprised that he's only asking for one year, I'd expected two,” he said.
“The old bastard's crazy.”
Speaking after Roswall, Peter Danowsky, who represents the recording industry association Ifpi, said he wanted to correct a number of misconceptions about the case.
He emphasized that file sharing as a whole is not on trial, but rather the four defendants – Fredrik Neij, Gottfrid Svartholm Warg, Peter Sunde and Carl Lundström.
Nor is the case about what sort of legislation ought to be passed with respect to file sharing, he said.
“The case is about whether the activities carried out by The Pirate Bay violated applicable laws and what the legal consequences should be,” said Danowsky.
He added that the trial is also about Swedish copyright in the digital age.
“And whether rights holders should have no protection or if they should have the right to earn a living,” Danowsky said.
He urged the court not to give weight to claims by the defence that people can download copyright protected material from other websites or that it's possible to find torrent files using Google.
“To say that ‘so many others also commit the same crime and therefore we shouldn't be convicted' doesn't hold, and that's something to which courts never give any consideration,” he said.
Danowsky reiterated music industry claims that the damages sought should cover not only record sales lost to The Pirate Bay, but the loss of goodwill and other harm caused by file sharing.
He then called into question the expert testimony of Roger Wallis from the Royal Institute of Technology (KTH), who argued that there are benefits to file sharing and that copyright as a system may have outlived its utility.
“Wallis's 30 percent guest professorship at KTH provides about as much credibility as something on par with a newspaper editorial,” said Danowsky, adding that the court should give more weight to testimony by Ifpi's John Kennedy and Ludwig Werner who “know what they are talking about”.
Danowsky then attempted to cast doubt on a study carried out by Sunde which concluded that 80 percent of the material on The Pirate Bay is free from copyright protection.
“That has neither credibility nor relevance,” he said, adding that defence claims that record companies should hold individual file sharers responsible rather than The Pirate Bay are “a dead end”.
The four defendants are accused of running The Pirate Bay website and in so doing "promoting other people's infringements of copyright laws."
Founded in 2003, The Pirate Bay makes it possible to skirt copyright fees and share music, film and computer game files using torrent technology, or peer-to-peer links offered on the site.
Although the site claims to have some 22 million users worldwide, none of the actual material can be found on The Pirate Bay server itself.
Representatives of the movie, music and video games industry are asking for around 117 million kronor ($ 12.7 million) in damages and interest for losses incurred from tens of millions of illegal downloads facilitated by the site.
Lawyers representing the industry were to hold their summations later on Monday while the defence was scheduled to wrap up the trial on Tuesday.
The court is expected to take a few weeks to announce a verdict.