The National Party has appealed a ruling that it breached copyright by using Eminem's track Lose Yourself for a 2014 election ad.
The High Court last month awarded Eight Mile Style, the publisher of the hit song, damages, plus interest from June 28, 2014 – a total of about $600,000.
National has now filed an appeal with the Court of Appeal.
In its earlier ruling, the High Court ruled that would be the "hypothetical licence fee" that would have reasonably been charged for permission to use Lose Yourself in National Party advertising.
The court noted Eight Mile Style had exclusive control of the song's licensing, and rarely granted permission for the song to be used in ads.
However, no additional damages were awarded because the National Party's actions were taken after getting professional, commercial, and media advice. The court found the party had not been reckless.
Following the High Court decision, the National Party said it was disappointed with today's verdict - and is now pursuing legal action against the supplier and licensor of the music.
The National Party bought the track Eminem Esque from a company called Beatbox, which in turn bought the licence from California-based music library Labrador.