I don’t mean to concern you, but this is my understanding of what would happen if the hearing doesn’t go favorably: your husband would lose his license for a year, and then have to have the interlock installed again for another year (the time he’s had it on his vehicle wouldn’t count).
Somebody had to have taken a test for the device to have registered alcohol, let alone indicate that a test had been attempted in the first place. It doesn’t just go off by itself (I had my issues with it, but it never came up that I had a fail for alcohol on a test that I had supposedly taken while I was at work). Who took the test, then?
I’d have my ducks in a row for the hearing. You might consider at least consulting with an attorney who has experience with DMV hearings.
Again, I don’t mean to worry you, but this is serious business, and it will go a long way with the DMV hearing officer if your husband makes it obvious to him/her that he takes it seriously.
Please thoroughly read this thread for some good information and firsthand experiences with hearings. I don’t know of a better resource on the internet to read up on dealings with Monitech/NCDMV.
[edit: Biddy Boh is right-there is language all over the contract with Monitech that readings are presumed to be those from the person to which the IID restriction was assigned]