A mother who left her five children in a parked van while she gambled at SkyCity Casino was discharged without conviction last year, while in 2010 a man who left his 18-month-old son in a car outside a Wellington strip club was fined $200.
Sensible Sentencing Trust national spokesman Garth McVicar said the public was frustrated with judges handing down "pathetic sentences".
He said it was unbelievable that anyone responsible for a child could behave that way.
"The judges have a duty to make it clear that society doesn't accept that sort of behaviour.
"I think the courts and the judges are being negligent. Obviously the parent is the first person to be negligent, but the courts have got a duty to uphold the law and make sure society is as it should be."
Mr McVicar said there was a case for mandatory minimum sentences.
"Ultimately judges have only got themselves to blame if they're not going to use the full force of the law, particularly in cases where children are concerned," he said.
"We're going to see more of a movement towards mandatory sentencing - minimum sentences, rather than a maximum that's never being used."
Child, Youth and Family southern regional director Kelly Anderson said it was not involved with the child's family at the time of the incident last Thursday, but has had "some previous involvement".
Police notified CYF that the boy had been left in the street, and the child was placed with a caregiver.
Mr Anderson said the child was "doing well".
"We are working closely with the family to make arrangements for the future care of this little boy."
He said babies and young children should never be left without adequate supervision.
"We would advise anyone who comes across a baby in this situation to call the police.
"When we are alerted to children being left unsupervised, we ensure the immediate safety of the children and work with the parents and wider family to ensure the children are adequately supervised in the future."
ABANDONED:
* March 2013: A newborn baby was left in a car outside Porirua Pak'n Save with a note to call a mobile number if there were any issues. Police have not located the mother because the person who discovered the baby has not reported the incident.
* February 2012: Five children were left in a van while their mother and her partner gambled in Auckland's SkyCity Casino. The 29-year-old mother was later discharged without conviction while her 39-year-old partner was convicted and ordered to pay $132 court costs.
* April 2010: An 18-month-old boy was left in the back of a car in Wellington while his father visited a club attached to The Mermaid strip club. Wayne Ricardo Schwamm, then 42, was later fined $200 and ordered to pay $130 court costs.
- Additional reporting: The Star
