Lyric provider Genius has accused search engine Google of wholesale lifting of its product.
A song title search on Google generally yields a boxed version of the lyrics, alongside the usual search results.
When a song lyric is searched online, Google now offers up Genius content, without acknowledgement, in the search results, the start-up says.
Genius assembles and explains lyrics and also offers the backstory to songs.
It has also sourced hard-to decipher rap lyrics, which led to its initial suspicions when these were found under organic Google searches.
Genius had been personally supplied with the enigmatic lyrics to the song Panda, written by US rap artist Desiigner. These then turned up, without accreditation, on Google searches, alerting the start-up to the copyright infringment.
Genius says that this lifting of its product has diverted traffic and revenue from its site.
It also raises revenue by providing its content to streaming services such as Spotify. As a song is streamed, its backstory pops up on user screens through the Genius platform.
To prove that the search engine giant was lifting its content, Genius embedded a secret watermark into its lyrics.
Through use of alternating serif and sans serif apostrophes, Genius established over 100 times where it alleged Google has passed off content as its own.
The alternating apostrophes, put together and converted into morse code, spell out "red-handed".
Google doesn't create the lyrics content. It licenses data partners such as LyricFind to provide the content.
Google has said it is investigating the issues and will stamp out search results that do not “uphold good practice”.
As music publishers do not generally make lyrics available, the lyric content is licensed from third parties.
"We do not crawl or scrape websites to source these lyrics.
"The lyrics that you see in information boxes on search come directly from lyrics content providers, and they are updated automatically as we receive new lyrics and corrections on a regular basis," Google said in a statement.