Ellis, 26, was last week acquitted of conspiracy to defraud by a jury in Middlesbrough, Teeside. But speaking at a press conference to launch the IFPI's annual , CEO John Kennedy said that the fight would go on.
The IFPI says it is owed £180,000 in unpaid royalties from Oink, which is an invite-only file sharing website. Kennedy said that the IFPI would consider civil proceedings against Ellis in order to recover the costs.
Oink was shut down in late 2007 after British police raided Ellis' residence and arrested him. Oink only stored torrent files and not actual songs. Ellis' server also acted as a tracker, which facilitates the download of files using torrents.
Users were expected to share their own files as well as download files or they could be banned.
To prove its case for the charge, government prosecutors needed to show that Ellis dishonestly interfered with the rights of copyright holders, said one of his solicitors, Simon Rose of the firm Morgan Rose Solicitors. Ellis' lawyers argued there was no conspiracy, and that Ellis operated the site in the open.
"He didn't hide in a back alley," said Rose, who helped prepare Ellis' defence. "He did it with what he believed were good intentions."
According to The Guardian. however, Kennedy described the verdict as a "terrible disappointment". He said UK legislation is "out of touch with where life is these days."
"We will find other ways of going about it," he warned.
According to the IFPI annual report, roughly a quarter of all recorded music industry revenues now come from digital sales, but illegal file-sharing and other forms of online piracy are causing "severe damage".
In a statement, Kennedy said: "It would be great to report that these innovations have been rewarded by market growth, more investment in artists, and more jobs. Sadly, this is not the case.
"Digital piracy remains a huge barrier to market growth and is causing a steady erosion of investments in local music."
Speaking after the court case, however, Rose said of Ellis: "He didn't hide in a back alley. He did it with what he believed were good intentions."
Ellis had collected about £20,000 in donations from Oink users, which he planned to use to upgrade his servers for the service, Rose added.
It's hard to say if the case will set a precedent, as the availability of free music services such as Spotify has changed the music landscape since Oink was shut down, Rose said.
"I don't know whether it will really have any impact," Rose said.