The Independent Police Conduct Authority has cleared officers involved in two fatal pursuits last year of wrongdoing.
In the first crash, in Blenheim in March, Penelope Phillips died when 20-year-old Frances Stubbs fled a police checkpoint and crashed into a vehicle Ms Phillips was driving. Stubbs was convicted of drink-driving.
The women's families asked why police didn't confiscate Frances Stubbs's keys before she was able to drive off.
However the police do not have authority to remove keys until the level of alcohol in a driver's system is established.
Two people died in the second crash, in Onehunga in September.
Police tried to pull over a car whose occupants were suspected of being behind reports of a laser being directed at motorists.
The driver, Aaron Tulafona, 20, fled and crashed, killing two of his four passengers, Jaycheree Makakea and Joseph Tawhai, both aged 20.
Tulafona, a disqualified driver with several convictions, admitted manslaughter and other charges.
The authority found the police acted lawfully in both pursuits.
