Beatles' 'Twist and Shout' played in Eminem vs National case

Music has again reverberated through court on Tuesday, as US company Eight Mile Style tries to prove that the National Party infringed on Eminem's copyright in a 2014 election campaign.

A music expert has told a court that the tune used by the National Party in a television election advertisement was copied from Eminem's hit song 'Lose Yourself'.

Australian composer and broadcaster Dr Andrew Ford gave evidence at the Wellington High Court on Tuesday via video link from Sydney.

Dr Ford appeared as a witness for Eight Mile Style, a US-based copyright administrator that protects music rights on behalf of Eminem.

Eight Mile Style has taken the National Party to court after it used in a 2014 election campaign a piece of music called 'Eminem Esque', which was made by a company called BeatBox and purchased from a stock music library.

National denies it infringed on copyright, saying it purchased and licensed the music legally.

But Dr Ford said 'Eminem Esque' was without a doubt a copy of 'Lose Yourself'.

"To sum up, 'Eminem Esque' substantially reproduces the key elements of 'Lose Yourself'," said Dr Ford.

He said the music that ended up in the National television advertisement was a "cut-down" of 'Eminem Esque'.

The cut-down version still featured the "sonic bed" from 'Lose Yourself', as well as the background chords and some drum patterns.

"They have the same staccato use of guitar, identical timbre, the identical chords or D Minor and G minor," Dr Ford said.

"It's clear that 'Eminem Esque' incorporates the essential features of 'Lose Yourself', " Dr Ford said.

When cross-examining Dr Ford, BeatBox's lawyer Mark Kelly suggested it was not uncommon for popular songs to share key aspects and features.

To make this point Mr Kelly played in court The Beatles' 'Twist & Shout' and 'La Bamba' by Los Lobos.

Mr Kelly then played a series of other well-known songs to the court, suggesting they incorporated key elements of 'Lose Yourself'.

These songs included 'Kashmir' by Led Zeppelin and 'Total Control' by The Motels.

Asked if the guitar parts in these songs were similar to 'Lose Yourself', Dr Ford questioned this and didn't completely agree.

Dr Ford said the creators of 'Eminem Esque' went out of their way to create subtle differences so it wouldn't sound identical to 'Lose Yourself' - but that didn't hide the fact it was a copy.

"I can't imagine a way 'Eminem Esque' was created without close recourse to 'Lose Yourself'," Dr Ford said.