The National Party is facing legal action over the alleged use of a song by US rapper Eminem in one of its election ads.
National's original rowing advertisement had a riff similar to that of Lose Yourself, the theme song for 8 Mile in which Eminem played a struggling rapper.
Today Detroit-based Eminem Publishers announced it was suing the party for alleged copyright infringement.
"In proceedings filed today in the Wellington Registry of the High Court of New Zealand, Eight Mile Style, LLC and Martin Affiliated, LLC, the Detroit-based publishers of Eminem's copyrights, are seeking damages for copyright infringement against the New Zealand National Party," a statement read.
"The proceedings stem from allegations that unauthorised use has been made of Eminem's Grammy and Academy Award winning song, Lose Yourself, in election campaign advertising run by the National Party in the lead up to the 2014 New Zealand General Election which is to take place on 20 September 2014."
Garry Williams, a commercial lawyer, confirmed he had been engaged in the action, noting that it was the owners of Eminem's song, not the artist himself, taking the action.
The National Party admitted it had received a complaint but was completely rejecting the allegation.
Campaign manager Steven Joyce said they had gone through all the necessary licensing procedures.
"We think it's pretty legal, we think these guys are just having a crack and have a bit of an eye for the main chance because it's an election campaign.
"We've got all the licensing, we've told them that and made it clear again this afternoon. We also incidentally moved on from this song about two weeks ago at the same time they first started to raise questions," Joyce said.
"I think they're just trying to shake us down for some money before the election."
Joyce said the track was licensed with the distributors and publishers.
"We also sought assurances from AMCOS and APRA that we could use it, and they were all given."
National paid the standard licensing fees and the track had been used by other agencies in the past, Joyce said.
"Nobody else has had any trouble with it, it just seems that picking on a political party might be flavour of the week - fair enough."
Joyce acknowledged the party had had an issue with a Coldplay song in 2008, "but this is an entirely different thing".
"We'll be defending it rigorously too."
Joyce said the song was chosen by the advertising team because it was a "positive upbeat track"'.
"We decided in the end it was a bit too positive, actually, which is why we switched to the other track."
Asked if he liked Eminem, Joyce said "not particularly"
"In fact I don't think I'd be in a position to describe whether it was or wasn't an Eminem song, it's not something that is in my era, sadly.
"I'm a little too old for that."
Joel Martin, speaking on behalf of the publishers, said they were not approached for permission to use any of Eminem's songs for the ad.
"It is both disappointing and sadly ironic that the political party responsible for championing the rights of music publishers in New Zealand by the introduction of the three strikes copyright reforms should itself have so little regard for copyright."
Martin said Lose Yourself was "one of the most iconic copyrights in the world and the song's publishers have rarely authorised its use to advertise products and have said that they would never allow it to be used in connection with any political campaign".
According to the statement, the publishers have previously sued Apple for using an Eminem song in a commercial spot without permission.
There has also been a high profile dispute with Audi in which the publishers alleged that it had wrongfully used a substantial reproduction of Lose Yourself in its advertising.
National has got itself in trouble before for its choice of music.
In 2008 it was warned about a piece of music marking John Key's first year as leader that sounded similar to Clocks by British group Coldplay.
Key had to order a recall of 20,000 DVDs featuring him in a video called Ambitious for New Zealand after Coldplay's record company, EMI, warned National it was breaching copyright by using music similar to the smash hit Clocks.
National Party campaign manager Jo de Joux previously insisted the music had been commissioned from an Auckland artist and was original.
"We paid these guys to make a DVD for us. We relied on their expertise and they have let us down."
Key said National should not have relied on Production Shed.
In 1984 Warner Bros threatened to sue the party for breach of copyright after the theme song for the Chariots of Fire soundtrack was used in an ad.
Should the speed limit be raised to 110kmh on some roads?Related story: 110kmh limit moves closer