Crown prosecutor Mike Smith called for a term of imprisonment, saying that was needed to deter others.
"More defendants are to come, and the court needs to set a benchmark. The appropriate benchmark is imprisonment."
Barker's lawyer, Jonathan Natusch, however, said jail would mean the end of a cleaning contracting business he had built up over 20 years and the likely loss of the home he shared with his son, who he had brought up as a solo parent since the boy was 3 years old.
Natusch said Barker had cooperated with the police, handing over his passwords and electronic devices immediately, and was prepared to act as a witness against the victim's boyfriend – potentially sparing her the trauma of a trial.
After the charges were laid Barker had gone to a number of people in the Kaitaia community to explain what he had done.
"He has seen his standing fall dramatically, and that is a source of distress to him, in the eyes of everyone he knows."
Judge Deidre Orchard took three years' jail as a starting point for the underage sex charge and added a year for contracting sexual services with an underage person.
She then reduced the sentence for his early guilty plea, previously unblemished character, cooperation with police, and willingness to testify against his co-offender. That resulted in a term of two years' jail, making him eligible for a sentence of home detention.
"Not only did you cooperate with police from the beginning, you made a formal statement against the young man who was effectively prostituting his girlfriend ... that may well end in a plea of guilty, which will spare the complainant the ordeal of court."
Barker was sentenced to 12 months' home detention and ordered to pay $1000 reparation to the victim for emotional harm.
Judge Orchard said the outcome for Barker's type of offending was almost always prison because of the need for deterrence.
However, she had been impressed by Barker's previous good character and dedication to bringing up his son, things she rarely saw as a judge.
"There is an exception to every rule, you deserve to be the exception."
Barker's sentence should not be seen as a precedent for the other defendants awaiting sentence, she warned.
A spokesman for lobby group Stop Demand, Mike Shaw of Kaikohe, was present in court. He said the sentence was a "terrible precedent" and "a joke".
A 15-year-old was still a child and could not legally consent to sex, he said.
''We've got to start treating the sexual violation of our kids as serious crimes,'' he said.
Another hearing will be held on October 2 to decide whether Barker should be placed on the sex offenders' register.
Judge Orchard believed Barker was at low risk of re-offending. A search of his devices and internet activity uncovered nothing else of concern, suggesting his offence was a one-off rather than a predilection for young girls.
Owen Sigley, 66, and Auckland church leader Michael Weitenberg, 54, have also admitted receiving sexual services from the 15-year-old complainant.
They are due to be sentenced next month.
Another, Calvin Fairburn, 37, of Kerikeri, denies sexual connection and contracting sexual services with a 15-year-old girl.
The victim's boyfriend has denied all 20 charges against him, which include sexual violation of girls aged 14 and 15.
