If everyone behind New Hampshire’s new voter registration law agreed on what it did, perhaps it would have been upheld in court in its entirety. Alas, on Monday State Superior Court Judge John Lewis threw out part of the law, almost certainly because of confusion over what the law actually did.

First, some definitions. Under New Hampshire’s law and constitution, people who have a “domicile” in New Hampshire and are otherwise qualified to vote may vote here. A domicile for voting purposes is “where a person, more than any other place, has established a physical presence and manifests an intent to maintain a single continuous presence for domestic, social, and civil purposes relevant to participating in democratic self-government.”

That is not the same as a legal residence, which the state defines as “The place of abode or domicile is that designated by a person as his principal place of physical presence for the indefinite future to the exclusion of all others.”

This past summer, the Legislature passed Senate Bill 318, which House Speaker Bill O’Brien says made the definition of “domicile” the same as the legal definition of residence. That would mean that to vote in New Hampshire, one would have to be a legal resident, which includes other duties such as registering one’s car in the state.

O’Brien says that was made clear by SB 318’s changes to the state’s voter registration form. Specifically, these two paragraphs, which newly registered voters would have to sign:

“I understand that a person can claim only one state and one city/town as his or her domicile at a time. A domicile is that place, to which upon temporary absence, a person has the intention of returning. By registering or voting today, I am acknowledging that I am not domiciled or voting in any other state or any other city/town.

“In declaring New Hampshire as my domicile, I am subject to the laws of the state of New Hampshire which apply to all residents, including laws requiring a driver to register a motor vehicle and apply for a New Hampshire’s driver’s license within 60 days of becoming a resident.”

O’Brien says that a residence is a type of domicile. Because one cannot legally be domiciled in two different places, one therefore cannot be a resident of another state (which requires that one be domiciled there) and also be domiciled for voting purposes in New Hampshire. Therefore, declaring oneself domiciled in New Hampshire for voting purposes necessarily makes one a New Hampshire resident.

Logically, that makes sense. Unfortunately, SB 318 was not clear on that. It was so unclear that in interviews Tuesday, House Legal Counsel Ed Mosca disagreed with Speaker O’Brien on what the law did, and the Attorney General’s Office, defending the law in court, did not argue that it required voters to be residents.

Judge Lewis asserted that the law did not do precisely what O’Brien asserts that it does do — make every New Hampshire voter a New Hampshire resident.

Maybe a law this confusing needs to go back to the drawing board.