A recidivist drink driver was today jailed for four years for killing a Northland mother while driving with nearly double the legal alcohol limit.

Warren John Jenkins, 49, of Orewa, north of Auckland, admitted driving with excess breath alcohol causing death and four related charges when he appeared in Auckland District Court today.

The court was told it was his 18th drink driving conviction and 19th for driving while disqualified.

Judge Emma Aitken set a non-parole period of two years saying his was the worst offending of its kind and had the option been available to her she would have given him a harsher sentence.

The charges followed the death of solo Kerikeri mother Katherine "Rin" Kennedy, 46, after Jenkins' car drifted across crossed the centre line of State Highway 10, just south of Kerikeri in the Bay of Islands, and the vehicles collided head-on.

Ms Kennedy was airlifted to Whangarei Hospital where she died several hours later.

Jenkins returned a blood-alcohol reading of 146mg of alcohol per 100ml of blood - nearly twice the 80mg legal limit.

In his victim impact statement, Ms Kennedy's brother Hamish Kennedy said his family felt betrayed by the justice system, which had not prevented Jenkins from driving after so many previous convictions.

"I always assumed that one of the main objectives of our legal and judicial system was to protect society from people like this. This is not what I have observed, I have been struck by the unfairness of a system that appears biased towards protecting the rights of criminals over delivering the protection and justice that I had taken for granted."

He described Ms Kennedy as a kind, witty, considerate and caring person who always did the right thing and had so much to offer society.