A group of police officers who allegedly broke the leg of an arts student and told her ''we don't care if it's legal'' have been allowed to change their defence at the eleventh hour after CCTV footage of the assault emerged.

Rachel Gardner is suing the NSW police force claiming she was kicked, sat on, handcuffed, pushed against a fence, loaded into a paddy wagon and then dumped at a nearby train station without charge after being caught without a train ticket on March 13, 2011.

CCTV footage emerges: Victim Rachel Gardner. Credit:Nick Moir

Police initially denied the kick occurred but sought to amend their defence in the Sydney District Court on Monday, minutes before the beginning of a five-day trial, after Ms Gardner's legal team revealed they had obtained CCTV footage from Cronulla station.

On Tuesday, Judge Sharron Norton lambasted the force's barrister Matthew Hutchings for presenting an "entirely different" defence document on the morning of the trial but she allowed it and deferred the trial to November.