The Exclusive Brethren member who killed his wife, daughter and a family friend in a car crash has been sentenced to four months community detention and disqualified from driving for one year.

Sentencing for Russell Stewart, an Exclusive Brethren church member in Northland - who admitted causing the deaths of three people, including his wife and daughter - was held at the Whangarei District Court this afternoon.

Judge de Ridder said since Stewart should have taken care on that stretch of road, having driven on it many times.

Crown lawyer Kyle MacNeil said Stewart's driving fell below the required standard, but he agreed with the defence a non-custodial sentence would provide sufficient denunciation and deterrence.

Russell Stewart in court.
Russell Stewart in court.

Defence lawyer Anthony Rogers said 49 character witness statements have been filed for Stewart who was described as a person of good character. He had no previous convictions, he said.

Stewart, 49, a businessman from Kaiwaka pleaded guilty on January 29 to three counts of careless driving causing death and four of careless driving causing bodily injury.

He was initially charged with three charges of aggravated careless driving causing death, four of aggravated careless driving causing injury, and one of failing to stop to check injury after an accident.

The guilty pleas came on the first day before his jury trial, which was scheduled for four weeks, began.

Offenders on community detention are subject to electronic monitoring and must wear an anklet 24 hours a day, seven days a week during their sentence.

Standard conditions can include reporting regularly to community probation, restrictions on living and working arrangements and limiting an offender's ability to move to a new residential address.

Stewart caused the deaths of his wife, Susanna Stewart, 48, their daughter Sadie, 16, and friend James Wearmouth, 18, when a ute he was driving crashed into a tree on Baylys Coast Rd about 6.45pm on June 6, 2016.

Susanna and James Wearmouth died almost immediately after the crash. Stewart's daughter, Sadie, died shortly after from her injuries.

The family were on their way home from Baylys Beach with other members of the Exclusive Brethren community near Dargaville when the vehicle crashed into a tree.

There were eight passengers in the five-seater Mitsubishi Triton and Stewart was behind the wheel.

Stewart was over the legal limit for alcohol when breath tested after the crash - 298 micrograms per litre of breath. The legal limit - lowered in 2014 - is 250 micrograms.

Members of his church, which has renamed itself the Plymouth Brethren Christian Church, were present when Stewart entered guilty pleas in the Whangarei District Court last month.

Aggravated careless driving causing injury or death carries a maximum penalty of three years in jail or a maximum fine of $10,000 plus mandatory disqualification from driving for one year.