National Party's Eminem rap battle has reached John Oliver

John Oliver says watching footage of Eminem's court battle against New Zealand's National Party is "everything I need right now".

The news comedian opened the latest episode of his hit HBO show Last Week Tonight by addressing the court battle playing out in the High Court in Wellington.

Lawyers are arguing whether a rip-off of Eminem's Lose Yourself was used for a National Party campaign ad in the 2014 general election.

Oliver quickly found the funny side.

"The track they used is literally called 'Eminem-esque'," he quipped. "If you're going to rip off someone else's work, maybe don't include the name of the person you're ripping off.

"Call it something less obvious, like 'This may or may not be copyright infringement'."

Oliver then played a clip of lawyers sitting motionless while listening to the original version of Lose Yourself, calling it, "the greatest thing I've ever seen".

"Some define comedy as tragedy plus time, but for me the purest definition is a Kiwi in a robe playing Eminem's Lose Yourself to a completely silent and motionless court room."

He went on to mercilessly mock the Kiwi accent.

Oliver ended the segment by saying, "There is nothing I want more than to spend the rest of the show breaking down what is projected to be a six-day court case," but he instead had to move onto other news.

Oliver has often poked fun at New Zealand in his show, covering the flag referendum, Steven Joyce being hit in the face by a dildo, and John Key and the ponytail incident.

His Eminem bit opened a show which mostly dealt with the issue of net neutrality, something Oliver covered back in his first season with great success.

Watch the full episode below: