Act MP David Garrett thought going to a cemetery, copying the details of a dead two-year-old baby and using those details to obtain a fake passport was "a bit of a lark".

According to the police summary of facts, Garrett created a fake Christchurch postal address and also made up a referee's name to obtain the passport.

When Garrett was first approached by police he denied the offence, but admitted it at a later interview.

He told police the reasons he applied for the passport "were delusions of grandeur".

Garrett told police he saw it "as a bit of a lark and frankly doubted that it would work".

He said he never used the passport and destroyed it in 1988, after discussing it with another law student.

In the passport application, which included the dead baby's name, still suppressed by the courts, Garrett included a photograph of himself disguised with glasses and dyed hair.

The application was processed and Garrett received a passport.

Garrett told police that he filed the application after reading the thriller novel The Day of the Jackal, in which the main character gets a passport by using the stolen identity of a dead person.

At a hearing into the offence, a police sergeant produced a letter from the dead boy's mother and sister.

In Judge K. de Ridder's sentencing notes from 2005, the mother and sister spoke of the anguish caused by Garrett's actions.

He said the mother of the boy expressed "deep sorrow and shock" after learning Garrett had stolen the identity of her dead son.

She described Garrett's actions as "stealing from the grave".

The dead boy's sister was also quoted by Judge de Ridder.

"The deeply cruel, shameful and malicious manner in acquiring such details is akin to literally stealing from the grave and has caused deep distress for the entire family, especially for my elderly mother, to be subjected to further trauma and pain in the memory of her beloved infant son and our darling little brother's name."

Judge de Ridder said it was obvious time had not healed the hurt of the family's loss of their son.

"In cases such as this, where the identification of a deceased person is used, there is a considerable amount of hurt to the family of the deceased, knowing that their son's identity had been abused in this way," the police summary of facts said.

Garrett's lawyer, Gary Gotlieb, told the judge that Garrett had an anxiety disorder and may have lost his legal practising certificate if he was convicted.

He had an anxiety depressive condition and was taking medication at the time of appearing in court.

Garrett asked to keep his identity secret to "maintain his reputation".

Garrett also told the court there was no chance he would appear before it again, and Judge de Ridder agreed.

Garrett was supported by three character references, none of whom are mentioned in the court record. One is believed to be Sensible Sentencing Trust founder Garth McVicar.

Police did not oppose name suppression, nor did they oppose discharge without conviction.

Judge de Ridder noted the premeditation required for Garrett's offence, which included going to the cemetery, copying details of a dead boy, filling in an application form, taking a photograph of himself with dyed hair and glasses and forwarding all the documentation to the Department of Internal Affairs.

The judge noted that 20 years had lapsed since Garrett's offending as "a roughneck".

"Obviously he is a million miles from that now."

The judge said that what saved Garrett from conviction was that he destroyed the passport and did not use it.

He went on to say that convicting Garrett would have a disproportionate effect to the crime committed and that there was no public interest in what Garrett did over 20 years ago.