Mr Potter, in a letter sent to the Police Complaints Authority in December 2005, said police interviewed Shane Cribb, then aged 17, after he collided with an unmarked police vehicle being driven by Commercial Vehicle Investigation Unit (CVIU) senior constable Neil Robert Ford in July 2005.
Mr Cribb had his conviction dismissed on Thursday, almost three years after the crash.
Attempts by the Otago Daily Times yesterday to contact police for comment were unsuccessful.
In a four-page letter to the Police Complaints Authority, Mr Potter said police unfairly and unjustly attached blame for the crash on Mr Cribb and denied Mr Cribb support when he was interviewed after the crash.
The letter said police would not allow Mr Potter to support Mr Cribb during the interview.
Mr Potter yesterday told the Otago Daily Times police had later allowed Mr Cribb's stepmother to be at the interview.
In his letter, Mr Potter meticulously outlined the sequence of events surrounding the crash as he believed they had happened, and how police had described them, with accompanying drawings, and asked for the charges against Mr Cribb to be dropped.
He told the authority that either to pervert the course of justice to protect a fellow officer, or through an incompetent investigation that lacked thoroughness, the police had unfairly and unjustly attached blame for the accident to Shane Cribb and subsequently laid charges against him.
Judge I. A. Borrin replied in January 2006, saying the authority had no power to intervene in the prosecution process.
The authority could not direct the charges be dropped and the authority could not consider issues which were the function of the court to decide.
He said Mr Cribb could come back to the authority once court proceedings were concluded if he had any issues he wanted addressed.
Judge Borrin said he was required by law to notify the Commissioner of Police of all complaints received but he would not do that at that time, as the material Mr Potter had forwarded to the authority could be useful in Mr Cribb's defence.
Mr Potter wrote back in May 2006 telling the authority he wished to proceed with a complaint.
The letter also made several other complaints.
Judge Borrin wrote back reiterating his earlier comments, and advised Mr Potter to ensure he made any claims he planned to make to the High Court within the required time.
He also said he had forwarded the complaint to the Police Commissioner.
Mr Potter told the Otago Daily Times yesterday he had sent a total of five letters to the Police Complaints Authority, now called the Independent Police Conduct Authority, and each time he was told it was before the courts and it was a police matter.
"I kept telling them I was not interested in them getting involved in the judicial process.
"I was only interested in them investigating the police that caused the judicial process to be required in the first place," he told the Otago Daily Times yesterday.
A letter had also been sent to police commissioner Howard Broad urging him to intervene.
Commissioner Broad acknowledged receipt of the letter and no further correspondence was received from him, he said.
