An ignition interlock device or IID is a small breath-testing machine. It’s installed in a car after someone gets a DWI (driving while intoxicated). It connects to the car’s ignition. Before starting the vehicle, you need to blow into the system. The IID checks your breath for alcohol. If it detects any issues, the car will not start.
In New Hampshire, the law requires an IID for certain DWIs. The state makes it mandatory for severe cases, such as an aggravated DWI or a second DWI.
When the court orders an IID
New Hampshire law says that if you get convicted of an aggravated DWI or a second DWI, you must install an IID to get your license back. The law, not the judge, decides this rule. You usually have to put one on every car you own or drive. The device stays installed for a set time, usually one year (12 months) to two years, depending on the case.
Costs and daily use
Drivers pay for everything, including the cost to install the IID and a monthly fee to check it. The device records every breath test and punishes anyone who tries to mess with it.
Drivers also take rolling retests. The device requires another breath test while you drive to ensure no one else has blown into it to start the car. These rules help the state keep roads safer while still letting people drive to work, school or treatment.
Why understanding IID rules matters
Understanding how these devices operate enables you to comply with the law and avoid additional penalties. Missing a test or driving a friend’s car without an IID can result in additional fines or a longer suspension. If you face a DWI charge, learn the rules and talk to a lawyer who can help you protect your driving record.
