The Independent Police Conduct Authority (IPCA) has been served a complaint from a free speech activist union on behalf of a peaceful protester who was arrested and locked in a police van after holding a sign during a pro-Palestinian march.

The protester, criminal barrister Lucy Rogers had purchased a piece of A2 paper and written on it the words "Selective Condemnation of Genocide is Evil" - holding it up to Palestinian protesters marching down Auckland's Queen St on Saturday. 

According to her post on Kiwiblog, Rogers said her actions were "silent and peaceful", yet she ended up being accosted by a group of nearby police officers who handcuffed her. 

Rogers was allegedly not given her sign back and was threatened with arrest for breach of peace, as well as failing to comply with the lawful order of a police officer if she didn't move on. She was only released when she agreed to immediately leave the scene and not return. 

Free Speech Union, which spoke out on Monday against Rogers being accosted and called the actions of the police "appalling", revealed on social media yesterday they have submitted an official complaint to the IPCA over the matter. 

"We’ve expressed our deep concern over the disregard for free expression rights and await their reply," the union wrote on social media. 

When initially approached by ZB Plus over the matter, Acting Superintendent Jacqui Whittaker, Relieving Auckland City District Commander explained police were required to engage with a female "whose behaviour gave rise for concern".

She said Rogers' attempts to antagonise people rallying along Queen Street "was deemed to meet a threshold where a serious disturbance or violence between parties could eventuate".

"Police applied a graduated response to dealing with the situation, which saw the female arrested for breach of the peace but was subsequently released and received a warning a short time later, once the safety risk to all parties had been mitigated," said Whittaker. 

"Our role in any protest action is to uphold the law. Police recognise the right to peaceful protest as well as the public’s right to go about their lawful business.

"During this, and other previous planned gatherings, Police have taken an approach appropriate to the circumstances and this has included engagement and monitoring as well as enforcement action in response to unlawful behaviour.”