One of the top music-related searches on the internet is song lyrics, but did you know that every time you Google the words to your favourite song, you are potentially helping music piracy?

Song lyrics – just like the music they’re from – are copyrighted material, but unlike the songs those stanzas score, they are not the property of record labels but music publishers.

While some lyrics websites pay the necessary rights to reproduce those words online, a lot of them – especially the more popular ones – don’t and where a lot of the bigger sites bring big traffic, they bring advertising revenue, and publishers are starting to realise that there’s a tidy, profitable economy that they’re missing out on.

Whether you consider it cashing in on what’s become a very valuable commodity, or standing up for the rights of music-makers, music publishers have turned their attention to the lyrics copyright battleground, firing the first shots in a legal war on unlicensed song lyrics websites, claiming that many of the ‘unofficial’ lyrics pages are profiting from intellectual property that isn’t rightfully theirs.

The National Music Publishers Association (NMPA) has kickstarted takedown notices this week at websites it claims have not obtained the necessary licences to publish lyrics, as Billboard (via music blogger Alan Cross) reports. The publishing masthead claims that more than 5 million searches for song lyrics happen daily on Google, and over 50% of those searches are directed to unlicensed lyric sites.

The NMPA has issued notices and cease and desist writs to a Top 50 ‘hit list’ of offending online lyrics sites, compiled by an October report from musician and University of Georgia researcher David Lowery, demanding that the sites obtain licenses or remove the copyright-breaching lyrics, in the first steps towards more serious legal action. [do action=”pullquote”]Song lyrics – just like the music they’re from – are copyrighted material… not the property of record labels but music publishers.[/do]

“This is not a campaign against personal blogs, fan sites, or the many websites that provide lyrics legally,” says NMPA Chief Executive David Israelite, emphasising the music publisher representative is gunning for commercial websites in “targeting 50 sites that engage in blatant illegal behaviour, which significantly impacts songwriters’ ability to make a living.”

At #1 with a bullet is Rap Genius, a popular crowd-sourced lyric site that offers explanations to the dense meanings and cultural references in hip-hop, RnB, and soul songs via annotations written by thousands of savvy fans.

The New York startup, which recently christened its Rock Genius spin-off lyrics site, benefited from a $15 million investment from Silicon Valley venture firm Andreessen Horowitz. But as Digital Music News points out, a large chunk of that change could be spent on litigation fees if the site becomes the primary target of the NMPA’s copyright crosshairs.

Ilan Zechory, co-founder of Rap Genius tells Billboard that they had to received a legal notice from the NPMA, “but we can’t wait to have a conversation with them about how all writers can participate in and benefit from the Rap Genius knowledge project,” he says.

The New York entrepreneur adds that Rap Genius goes above and beyond a simple song lyrics site with its interactive annotations. Unlike the other 49 sites targeted by the NMPA, “these layers of context and meaning transform a static, flat lyric page into an interactive, vibrant art experience created by a community of volunteer scholars,” says Zechory.

From a monetary standpoint, it’s unclear how much money the NPMA believes unlicensed song lyrics sites are profiting from – especially considering Rap Genius doesn’t have clear advertising on its site – but considering the costly expense of litigation it’s prepared to undergo, it must be worth the complicated court attack. [do action=”pullquote-2″]”This is not a campaign against personal blogs, fan sites… [we’re] targeting 50 sites that engage in blatant illegal behaviour, which significantly impacts songwriters’ ability to make a living.”[/do]

Besides, the NPMA has already tasted victory in this field, last year winning (on behalf of Warner Chappell Music, Peermusic, and Bug Music) a $6.6 million judgement against LiveUniverse, the company of MySpace co-founder Brad Greenspan that operated an umbrella of unlicensed lyrics sites.

The NPMA’s Top 50 list is based on a report from David Lowery, of the bands Camper Van Beethoven and Cracker, whose ‘Undesirable Lyric Website List’ (available to read in full here) seeks to illustrate the little-known public fact that unlicensed song lyrics sites are breaching copyright, while illustrating to the potential of the offending sites in generating large amounts of advertising dollars from the huge search engine traffic.

“Based on the popularity of lyric searches, it is possible that unlike the sound recording business, the lyric business may be more valuable in the Internet age,” Lowery writes in the report.

“Indeed, the vast majority of these websites seem to have well established monetization schemes based on advertising. Many of the sites appear to have accounts with major online advertising exchanges and prominently feature advertising from major brands. There are even companies that appear to specialize in matching specific lyrics to key demographics for advertisers.”

“These lyric sites have ignored the law and profited off the songwriters’ creative works, and NMPA will not allow this to continue,” adds NMPA’s Israelite.

You can view Lowery and the NPMA’s Top 50 hitlist below.