Two off-duty cops allegedly battered a group of students with a series of punches and kicks after forcing their way into a central Auckland apartment building, a court has heard.

Auckland City police constables Patrick Garty and Wiremu Bowers Rakatau are charged with common assault relating to the altercation that occurred about 1am on March 18, 2009,

Garty faces three charges and Rakatau one charge. The men are jointly charged with a further count of common assault.

The allegations are being challenged at a defended hearing underway at the Auckland District Court today.

The court heard Garty and Rakatau were walking along High St when they came across a group of students walking in the same direction on the other side of the road.

Prosecutor Eilidh Hook said one of the students started playing with a shopping trolley "for between nine and 14 seconds" and was verbally challenged by Garty.

The verbal exchange continued as they continued walking up the street and when the students turned down Little High St to go into the Soho apartments.

Ms Hook told the court today one of the students, Benjamin Palmer, gave Garty the fingers in an "enthusiastic " manner.

The constable changed direction and followed him to the apartment entrance and is alleged to have assaulted Thomas Campbell, another man in the group, knocking him to the ground with a "double handed strike to the chest area".

The blow caused him to fall back onto the alcove entrance.

Mr Palmer opened the apartment doors that allowed him and the others access to the apartment foyer and kept the door ajar to allow Mr Campbell inside.

Garty moved past him and forced the door open to gain access to the alcove.

"He has gone after Palmer ... Garty moved towards him, taking a fighting stance, striking him in the chest with a double handed strike.

"That was followed by a series of punches to the head and face," Ms Hook said.

He stopped momentarily to confront another member of the group, Vincent Burns, who he struck with an "open handed punch".

Ms Hook said Garty returned to Mr Palmer landing a "further series of punches to the head and face" which caused him to fall back and "strike his head against the stairwell as he collapsed on the floor".

At the same time as he turned back to Palmer Rakatau "forced himself" between Garty and the other members of the group forcing them back into the foyer and preventing them from aiding Mr Palmer.

Rakatau is then alleged to have deliberately kicked a student five times in the knee area. The prosecution alleged this action allowed the assault on Mr Palmer to continue.

The hearing is expected to last three days and will hear from 29 witnesses.

A third officer, Constable Chris Renata, is also charged with common assault arising from the incident.

He faces a defended hearing later this year.