Will the driver have to keep the Interlock for 1 or 3 years?
A good question and one that reminds us that the driver arrested for DUI is facing a big and little shotgun barrel. The big barrel is the court system which could have subjected the driver to 364 days in jail for a DUI 3rd offense. Obviously taking a plea to DUI 1st offense is good for the driver, well better than going to trial, losing, and being sentenced to mandatory jail time.
But as this question points out, there is still the little shotgun barrel which is the New Mexico Motor Vehicle Division (MVD). They are little because they cannot put you in jail, impose a fine, or require so many hours of community service. MVD giveth and taketh away your privilege to drive. As you already know, in New Mexico first DUI offenders have to do one year with an interlock license and the Breath Analysis Ignition Interlock Device (BAIID) in their vehicle, second offender must keep the license and device for two years and third offenders will not receive a full license until three years from the date of installation.
The trouble is, MVD can ignore your plea bargain in court. Even though as far as the judge is concerned this is your first offense, MVD will require that the driver maintain an Interlock license for the full three years because in the MVD computer this is a third DUI offense, not a first.