Mandating Interlocks for Fully Revoked Offenders: The New Mexico Experience

Abstract

Objective. In New Mexico, between July 1999 and December 2002, the installation of an ignition interlock was an optional judicial sanction for second and third driving-while-impaired (DWI) offenders. This is a study of the recidivism of 437 offenders who were convicted and installed interlocks for an average of 322 days during that period.

Methods. The comparison group was a stratified random sample (N = 12,554) of the 20,949 offenders who were convicted during the same period but did not install interlocks. DWI arrest and conviction data for all study participants were received from the Motor Vehicle Department's Citation Tracking System.

Results. Only 11 (2.5%) of the interlock offender group were rearrested for DWI while interlocks were installed, whereas 1,017 (8.1%) of the comparison group were rearrested during an equivalent 322-day period. Survival graphs and Cox proportional hazard regression analyses were used to compare the interlock and noninterlock groups during installation, after installation, and for the entire period up to December 2004. Results indicate a reduction in recidivism of 65% during installation. After removal, there was no significant difference in recidivism rates in a 3-year follow-up period. Following all offenders for 4 years, including both the period while the interlock was installed and the period after its removal, indicates that the difference in recidivism achieved during installation, though not increased, is maintained, so at the end of 4 years, interlock users still have lower total recidivism than nonusers.

Conclusions. The magnitude of interlock effectiveness reported here is similar to those in other published studies with comparable samples.

Keywords:

• DUI
• DWI
• Impaired Driving
• Interlock
• Recidivism
• Mandatory
• New Mexico

ACKNOWLEDGMENTS

This work was supported by the National Highway Traffic Safety Administration (contract number DTNH22-02-D-95121) and the National Institute on Alcohol Abuse and Alcoholism (grant number K05 AA014260). The results and opinions reported in the article are those of the authors and not necessarily those of the supporting agencies. The authors also express thanks to those who provided access to the Citation Tracking System and the Interlock Installation and Removal data: Larry Kehoe, Director of the New Mexico Motor Vehicle Department; Michael Sandoval, Bureau Chief of the New Mexico Traffic Safety Bureau; and James Davis, Director of the University of New Mexico Division of Government Research.

Notes

¹Those who refused were lumped with the high BAC group because recidivism curves for the two were indistinguishable.

²The 1999–2002 New Mexico interlock law specified interlocks as an optional sentence for second and third DWI offenders. Therefore, first offenders were excluded from our interlock group. Those with four or more DWI convictions were included in the “priors = 3” subgroup because many offenders with four or more DWIs are pled down to third misdemeanor offenses.