A Taranaki officer should have stopped a drunk driver getting back into his car before a fiery smash that killed three teenagers in August 2005, a coroner has found.
The findings echo an internal police report from 2007.
Constable Lincoln McRae left security camera volunteers to watch Raymond Hansen's car despite having been outrun by Hansen at up to 180km/h as he sped to a Hawera bar.
A radio failure then prevented police from hearing the volunteers' warning when Hansen drove off minutes before the fatal crash.
Mr McRae admitted at the inquest he wanted to catch Hansen in the car so he could be prosecuted.
Coroner Simon Shera says he should instead have impounded or immobilised the car and tried to find Hansen.
Mr Shera is calling for police to review how they make such decisions.
Hansen was sentenced to nine years' jail for manslaughter.
Central districts police promised more training for officers.