The Commerce Commission is being accused of not understanding the two-sided nature of the media market.
NZME and Fairfax have gone to the High Court in Wellington to fight the Commission's ruling that the two media giants are not allowed to merge because it would lessen competition.
NZME and Fairfax argue they're competing in a global media environment against the likes of Facebook and Google, and are struggling to stay afloat.
David Goddard told the court that the media is going through "intense and rapid change" as audiences move online and advertisers follow.
He says the media is only as good as the product it puts out, which attracts people and therefore advertising dollars.
Mr Goddard says the Commission ultimately adopted a static approach rather than a moving picture.
The appeal has been set down for 10 days.