A lawyer acting for Eminem's copyright administrator has refuted claims by the National Party that Eminem's song 'Lose Yourself' is of "low-level originality", saying the submission "lacks common sense".
National and its general secretary Greg Hamilton are defendants in a copyright trial brought by US-based Eight Mile Style, a company that represents Eminem in copyright claims.
Eight Mile Style is suing National after the party used a piece of production music called 'Eminem Esque' in a 2014 election campaign advertisement.
The company argues 'Eminem Esque' is a rip-off of the rapper's Academy Award-winning hit 'Lose Yourself'.
Earlier in the trial National's lawyer said Eminem's song has "low-level originality", arguing therefore using 'Eminem Esque' cannot be considered copyright infringement.
However Eight Mile Style's lawyer rejected that claim during his closing arguments on Friday morning in the Wellington High Court.
"The submission really defies common sense and the evidence," Garry Williams said.
Mr Williams said several international corporations had paid "significant sums" to license 'Lose Yourself' in the past.
The only reason they paid those sums was because the song was original and recognisable, Mr Williams said.
The question of originality has proven to be a key part of National's defence in this trial.
Yesterday its lawyer said Eminem's rapping and lyrics were the only truly original parts of the songs, and that the music itself was nothing new.
But on Friday Mr Williams said the "hypnotic guitar riff" is a famously recognisable part of the song.
National's claim the guitar riff is unoriginal is "disingenuous", Mr Williams said.
"While there are some differences, the essence and substance of 'Lose Yourself' has been taken."
Mr Williams argued that any damages should reflect the value of 'Lose Yourself', previous license fees, the absence of creative control and the "very strong" negotiating position of Eight Mile Style.
He added that the fact National's television advertisement had "gone viral" should also be considered.
As a guide, Justice Helen Cull will likely refer to previous fees paid for licensing 'Lose Yourself' for commerical use.
Those exact figures are confidential, but the court has heard the song demands licensing fees in the millions of dollars.
Justice Cull has reserved her decision, saying she hopes it won't be "too many months away".
If damages are awarded, any amount will be revealed as part of the judgement.