One of the big arguments at the Pirate Bay trial in Sweden is whether file-sharers are encouraged by their downloads to purchase more music or are deterred from buying any.

Lots more statistics were on show today on Day 8 of the court case in Stockholm, as studies were quoted by both sides to support their views. The pirates say that sharing music (illegally) encourages music lovers, who should not punished.

The music industry begs to differ and it had its day in court today in the person of John Kennedy, head of the International Federation of the Phonographic Industry.

Questioned on research that has been done into the impact of unauthorised file-sharing, Kennedy pointed to five studies that established a causal link between falling sales and unauthorised file-sharing.

They included US Professor Stan Liebowitz, who in 2007 concluded that the decline in sales had been wholly attributable to illegal file-sharing. A single study in 2004, which had reached a different conclusion, arguing that file-sharing helped promote legitimate sales, “did not hold up under examination according to a subsequent appraisal by Liebowitz," Kennedy said.

Kennedy said that people who download music from TPB spend much less on music than they would otherwise and if they didn’t get it for free they would buy it. “It is common sense, if they couldn’t get it for free they would buy it and when we ask them, they confirm that.”

Kennedy, a music business veteran, then ran through through the major complaints about illegal file-sharing and pointed the finger of blame directly at The Pirate Bay web site.

He said the music industry had lost more than 30 percent in sales since 2001 because of illegal downloading and told the court in Stockholm that the Pirate Bay had become "the No. 1 source of illegal music," following court actions against two other popular file-sharing sites, Grokster and Kazaa.

"Over a period of time, piracy has done immense damage to the music industry," Kennedy said, adding that illegal Internet downloads had caused industry sales to tumble from $27 billion in 2001 to $18 billion in 2008.

Kennedy was testifying on behalf of a handful of record companies, including Sony BMG and EMI, which together with movie companies such as Universal and Warner Bros. Entertainment Inc. are seeking 117 million kronor ($13.2 million) in compensation and damages.

"I believe they are justified and may even be conservative because the damage is immense," he said of the claim.

Gottfrid Svartholm Warg, 28, Peter Sunde, 30, Fredrik Neij, 30, and Carl Lundstrom, 48, are accused of breaking Swedish copyright law by helping millions of Internet users download protected music, movies and computer games for free through The Pirate Bay. They have pleaded not guilty.

Kennedy said The Pirate Bay had eroded legitimate music sales, harmed the environment for legitimate services, damaged the marketing plans of music companies and disrupted the flow of investment into new music.

He added that the Pirate Bay harms music copyright holders in a number of distinct ways. It deters people from buying music online, as well as new ventures and retailers wanting to enter the digital music market. There are also the wasted costs of marketing and of developing new artists, and a range of other costs, such as engineering and production.

One problem with Kennedy's testimony was that it did not go to the heart of the court case, which is that, as a search engine, can the Pirate Bay be convicted of assisting copyright theft?

Kennedy admitted he did not fully understand the technology involved in the site. The defendants say their site does not violate any laws because it does not host any copyrighted material. Instead, it directs users to other file-sharers, with whom they connect through so-called torrent files to download content. If convicted, the four would each face up to two years in prison.

So far the prosecution does not appear to have had a great deal of success in skewering the technicalities of The Pirate Bay's involvement in promoting illegal file sharing.

After his testimony, Kennedy told The Associated Press that the defendants were "hiding" behind their torrent technology, saying they still contribute in making copyright-protected works available to others.

"I want Pirate Bay to close down," he said. "I want some compensation and I want it to be clear people cannot steal other people's property without there being consequences."

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