Ashish Macwan (32), of Auckland, had pleaded guilty to a charge of causing the death of his son, Aarush, by careless driving near Cromwell on April 22, but was discharged without conviction when he appeared in the Manukau District Court yesterday for sentencing.
The family had stopped by the lake while on holiday and Macwan, who was driving, got out. The handbrake was not on and the van rolled into the lake with five passengers still inside.
Mr Lepper had earlier questioned the need to charge Macwan, saying the man had suffered enough.
"While I'm happy with the result, I do worry about the resources and pain involved in getting to this decision.
"I hope that some thought will be given to the necessity of charging people in similar circumstances in the future."
Mr Lepper and Central Otago District Council business development manager Jono Gadd were among the first at the scene of the accident and dived into the lake. Their rescue attempt was thwarted by the depth and coldness of the water and they were unable to reach Aarush, who was buckled into his car seat in the van, 5m under the surface.
"That day still haunts me and you will always wonder what else could have been done. I'm sure all involved feel that way. The feeling of helplessness remains and so does the image of the family trauma at knowing what had happened to their son - that's also pretty clear."
In cases like this, charges were a waste of time and money and served no useful purpose either as message to society or as a deterrent to others, Mr Lepper said.
Cromwell police head Sergeant Mike Williams stood by the decision to charge Macwan.
"It was appropriate to press charges and I stand by that.
"It's not the police's decision to decide on guilt or innocence - that's for the court to decide."
Given a similar set of circumstances again, he would still press charges.
"We have to look objectively, as we did in this case. We were not removed from the emotion of the situation. Every person who dealt with that incident has children of their own, so they're not removed from the emotion of the situation, but we have to be professional and deal with it objectively," Sgt Williams said.
Mr Gadd said the court result was "brilliant news".
"My view is that the whole purpose of the criminal justice system is for society to punish people for transgressions, but what could society ask of Ashish and his family, what could they ask or take from him that would compare with what he has lost already?
"He was a totally broken man and you could see how much emotion and grief the family was going through at the time."
