Smillie resisted arrest and was subsequently pepper-sprayed.
IPCA chairman Judge Sir David Carruthers said the authority accepted that Smillie's behaviour amounted to active resistance and that the officer was entitled to use the pepper spray against Mr Smillie in order to arrest him.
"However, the authority finds that the subsequent force used against Mr Smillie was unjustified," Sir David said.
Despite the use of the spray Smillie failed to calm down and the officer struck him with a police baton and pushed him against the fence in an effort to apply handcuffs, the report said.
Following this Smillie fell to the ground.
The officer then retrieved his Taser from his vehicle and warned Smillie he would be tasered if he continued to refuse arrest.
Footage from the stun gun showed the officer then released the taser for 13 seconds before attempting to handcuff Smillie, the report said.
The officer then picked up the taser and discharged it a second time before handcuffing Smillie and returning to his police car.
"The authority finds that the deployment of the taser on two occasions amounted to an excessive use of force and was contrary to the law," Sir David said.
"This was aggravated by the fact that on the first occasion the taser was used for an extended period of time of thirteen seconds. "The first use of the taser was not in self-defence, as claimed by the officer and given there were other options open to the officer short of using the taser, the authority considers Mr Smillie's arrest could have been effected less forcefully after waiting for the arrival of other police officers," Sir David said.
Following the incident Smillie was charged with assaulting police, possession of an offensive weapon, refusing to accompany and failing to stop.
However, police later withdrew the charges of assault and possession of an offensive weapon and Smillie pleaded guilty to the charges of refusing to comply and failing to stop.
"The Authority recommends that police take disciplinary action against the officer in light of its findings detailed in this report," Sir David said.
Following the incident Bay of Plenty police conducted a criminal investigation and sought legal advice in regard to the actions of the officer.
The decision not to prosecute was made following that "rigorous process", Bay of Plenty District Commander, Superintendent Glenn Dunbier said.
Police then considered the matter in the employment context, he said.
"We fully accept that the actions of the officer when using the taser didn't meet the high standards we expect.
"However we are satisfied his actions were not the result of any ill will or malicious intent," Mr Dunbier said.
"Our staff confront incredibly difficult and emotive situations on a daily basis and are making split second judgements and decisions without issue.
"We accept that the officer's judgement on occasion was flawed."
The officer had learnt from the situation and responded well to remedial action, he said.
"We note the IPCA's recommendation about disciplinary action.
"However the public rightly expects police to deal with these issues in a timely manner and we initiated remedial action through the employment process some time ago."
Because there was action taken at the time, they could not take different action now, Mr Dunbier said.
Between the national rollout of the taser on March 22, 2010 and June 30, 2012 a taser was deployed in Bay of Plenty 192 times. In 167 (87 per cent) of those incidents the situation was successfully de-escalated without the need to discharge the taser.
Prime Minister John Key said he did not want to "second guess" the police force's actions in regards to the officer.
"What I would say is that the general use of tasers by police have been not only within the law, but highly effective.
"The good news about tasers are they are a non-lethal option and if you contrast that with difference in the use of a weapon, that's a very, very serious issue."
There was no getting away from the fact that the IPCA report found that police "got it wrong", Mr Key said.
"I think the police have apologised for that and they are taking their own internal steps to rectify that.
"I still overall support the use of tasers, but police still need to stick to the law."
