The copyright case taken by the American rapper Eminem's publishers against the New Zealand National Party will finally be heard in court.

Photo: AFP

Detroit-based companies Eight Mile Style and Martin Affiliated are suing National over music used in the party's 2014 election campaign advertising.

The backing track to the rowing-themed video has been compared to Eminem's award-winning song, Lose Yourself.

A spokesperson for the publishers said in 2014 they had never allowed the song to be used in connection with any political campaign.

National has previously said it went through the proper licensing process before using the track.

The party described the music as library music and said it purchased it from production music supplier Beatbox, which is based in Australia and Singapore.

In 2008 National was forced to pull thousands of DVDs featuring a music track similar to a song by the band Coldplay after the record company EMI raised concerns.

The trial will begin in the Wellington High Court next May and is expected to run for three weeks.