Spotify, the fast-growing music-streaming service, has had an increasingly vocal contingent of musicians questioning whether its business model benefits the music industry as a whole. Now a record label is joining the mix, accusing Spotify of copyright infringement because of the way it handles playlists.

Ministry of Sound, a dance-music record label based in the U.K., is suing Spotify for user-generated playlists that mimic the order of the label’s popular compilation albums. The company, which is seeking to remove these playlists from the service and collect damages through a British court, argues that the curation of songs chosen for particular compilations is a form of intellectual property protected by copyright law.

“We painstakingly create, compile and market our albums all over the world. We help music fans discover new genres, records and classic catalogues,” company CEO Lohan Presencer wrote in an editorial in the Guardian. “After 20 years and more than 50 [million] album sales, the value and creativity in our compilations are self-evident.”

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The outcome of the suit could have big implications for the future of digital music. Services like Spotify, which provides access to millions of songs, are increasingly using playlists to help users make sense of the vast amount of music available. Spotify introduced a “browse” function in August through which it hand-selects quality playlists for listeners. Beats Music, an upcoming streaming music service by the company behind Beats by Dre headphones, touts playlists curated by music artists and experts as one if its greatest selling points. Songza, another service, is driven by human-selected playlists that are designed to align with specific activities and moods.

Whether these playlists — curated in much the same way as Ministry of Sound’s compilations — are under copyright protection could become a point of legal contention if users try to carry popular playlists from one platform to another. That’s exactly what some users are doing in this case, going so far as to label some playlists with the “Ministry of Sound” moniker.

“The usual practice would definitely be to register the collective album [for copyright protection], along with the artwork that’s on the album and things like that,” says Andy Sellars, a staff attorney for the Digital Media Law Project housed at Harvard University. “I’m not aware of a case where someone has tried to claim just the playlist.”

Illegally downloading a Ministry of Sound compilation album would be an obvious case of copyright infringement, but Spotify users are listening to individual tracks that have been legally licensed by the company. The label is upset because it has not reached an agreement with Spotify over licensing fees and Spotify has refused to take down playlists imitating the label’s albums. A Spotify spokesman said he was not aware of any past situations when the company had removed a user playlist for any reason.

In legal terms, Sellars says, the dispute comes down to whether songs that are streamed one at a time and don’t reside on a user’s hard drive exist independently or whether they should be viewed as a “collective work” because they are organized in a playlist. “If there’s a lawsuit in the United States, this would come down to a battle of metaphors,” he says.

If a court rules that the user-generated playlists qualify as illegal copies of Ministry of Sound’s creative, collective works, Spotify would be on the hook for creating an environment conducive to infringement and then doing nothing about it (think Napster or Megavideo).

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But given the ubiquity of playlists in today’s music environment, Ministry of Sound may have a tough sell. “Even if Ministry of Sound claims that ‘a lot of research’ went into compiling the list, what the public sees is just a list of nouns,” E. Michael Harrington, a music-business professor and member of the Future of Music Coalition advisory board, said in an e-mail. “Compiling a list of songs you like in a specific order deserves as much copyright protection as compiling a list of things one did in Manhattan today.”

Ministry of Sound says it’s fighting the good fight for an industry that has been at the mercy of tech companies since the iTunes Store launched a decade ago. “This is a David vs. Goliath battle, but one which we have no choice in fighting,” Presencer wrote.

With the playlist gaining increased importance as a form of music consumption, it’s a battle that could spill over onto other fronts later. “As technology companies get innovative with technology,” says Sellars, “rights holders get pretty innovative with the law.”