Watch: Early versions of National ad featuring 'Lose Yourself'

The trial involving the National Party and Eminem has been shown an early version of an election advertisement that featured the rapper's song 'Lose Yourself' accompanied by the voiceover of then Prime Minister John Key.

The videos are known in the advertising industry as 'animatics' and are shown to clients and focus groups.

The video, which also includes the voice of deputy Prime Minister Paula Bennett, was entered as evidence today in the Wellington High Court in the trial between US copyright administrator Eight Mile Style LLC and the National Party and the company that made the music.

Eight Mile Style has brought action against National over its use of a piece of music called Eminem-Esque it used in a series of television advertisements during the 2014 general election campaign.

Eight Mile Style alleges the piece of music is a copy of 'Lose Yourself', which when licensed and approved for commercial use demands license fees in the millions of dollars.

BeatBox, the company that composed 'Eminem Esque', is also a defendant.

National denies copyright infringement, arguing it's protected as it bought 'Eminem Esque' legally from a music library called Labrador and correctly licensed it.

Auckland television director Glen Jamieson from production company Stan 3, which was hired by National to make the advertisements, told the court the early versions featuring 'Lose Yourself' were not meant for the public.

"It's not for broadcast... it's only for an internal discussion," Mr Jamieson said.

He said 'Lose Yourself' was used in the animatic because he wanted a "contemporary track" with "a good beat" that would suit an advertisement featuring rowers.

Mr Jamieson said he engaged Auckland's Sale Street Studios to find production music to be used in the final version of the advertisement.

He told the court that as '"a guide" he suggested 'Lose Yourself' to Sale Street Studios.

The company returned with 'Eminem Esque', a piece of music Mr Jamieson said had the beat he was looking for, but "the tune was quite different" to 'Lose Yourself'.

Mr Jamieson told the court he showed a final version of the advertisement featuring "Eminem Esque" to National staff at their Auckland headquarters in May 2014.

He said one National staff member told him it sounded similar to 'Lose Yourself' by Eminem.

Stan 3 was then instructed by National to find alternative music however after exploring other options, 'Eminem Esque' was still preferred.

Mr Jamieson told the court that as it was possible to obtain a license of the track from APRA, it was "presumably" fine to use the track.

Eight Mile Style layer Garry Williams asked Mr Jamieson: "Wouldn't it have been prudent to seek the permission of the copyright controllers of 'Lose Yourself'?"

Mr Jamieson replied: "No, because it was available and had been available for years."

He said he used production music many times before and it was "very unusual to say the least" to have copyright problems.

"It's not that we were trying to be dodgy about it."

National's general manager Greg Hamilton has also given evidence today on behalf of the party.

Mr Hamilton said the party sought assurance from Stan 3 about potential copyright problems with licensing and using 'Eminem Esque'.

He said National received a response from Stan 3 that "this is the way things work" in the industry.

"Our approach was to trust and rely on the experts," Mr Hamilton said.

The case continues on Monday, with closing arguments set down for next Thursday and Friday.