The Government is being urged to change the law so that people jailed for driving offences cannot serve a licence disqualification while in prison.
Coroner Gary Evans made the recommendation in findings on the death of Debbie Ashton who was killed in 2006 by a repeat drink-driver who was in a police witness protection programme.
Mr Evans said imposing sanctions that have no practical effect seems to be a barren exercise.
Jonathan Barclay was sentenced to prison for 5½ years for manslaughter and served his three year driving ban during his time behind bars.
Transport Minister Gerry Brownlee said he would support a change to the Land Transport Act to ensure that a driving disqualification takes effect only after any jail sentence is served.
Officials are looking into the possibility of a law change and will report to the minister within a few weeks.
The case sparked a ministerial inquiry and a Government apology for failures by police and the Corrections Department.
Barclay was driving well above the speed limit, and on the wrong side of the road, when his car hit Ms Ashton's vehicle head-on at Richmond near Nelson in December 2006.
Two months earlier, Barclay had been given a final warning and disqualified from driving. He ignored that and drove again.
But when stopped with excess breath alcohol he used a name given to him by the witness protection programme, and was subsequently dealt with in court as a first-time offender. He is now out of prison.