Campaigners against plea bargaining have marched to Parliament to deliver what they call the "Moko petition", which has received thousands of signatures.
The campaign, led by the Sensible Sentencing Trust, follows the sentencing of Tania Shailer, 26, and David Haerewa, 43, who were able to plead guilty to manslaughter despite being charged with the murder of Rotorua toddler Moko Rangitoheriri.
Shailer and Haerewa were supposed to be looking after 3-year-old Moko while his mother was in Starship Hospital with her eldest child.
Instead, the pair tortured the 3-year-old, kicking, stomping, slapping him, and rubbing his faeces in his face. He was pronounced dead on August 10 last year.