This is a joint post with David Chudzicki. Neither of us are lawyers.

Somerville just introduced domestic partnerships:

Domestic partnership means the entity formed by people who meet the following criteria ...

Cambridge has a similar ordinance:

"Domestic partnership" means the entity formed by two persons who meet the following criteria ...

Like most, Cambridge's ordinance is limited to two people, but Somerville is novel in being open to more.

Both, however, recognize domestic partnerships from other jurisdictions. Here's Cambridge's:

"Domestic partner" means a person who meets the criteria set out in subsection D of this section or who is registered as such in another jurisdiction.

Since Somerville does not restrict domestic partnerships to residents, it looks to us like a group of Cambridge residents could register a Somerville domestic partnership, which Cambridge should then recognize.

We looked a bit for some other jurisdictions that might recognize Somerville group domestic partnerships, but only found municipalities. Looking at states, California explicitly limits to two, and Oregon and Maine don't recognize outside domestic partnerships. Some municipalties, like Boston and West Hollywood don't seem to recognize domestic partnerships from other jurisdictions, but others, like Provincetown, Nantucket, and Berkeley do appear to.

How does this interact with existing marriage law? Suppose Pat and Sam are married. Can they form a Somerville domestic partnership with Alex? The ordinance is unclear: one of the conditions is that "They are not married". Does that mean the people entering a partnership can't be married to each other? Or to anyone? If the latter, then they can't have a domestic partnership that includes Alex without getting divorced first. Maybe Pat and Sam could then remarry? If they can't remarry, then the situation is pretty rough from a tax perspective: they have to choose between two of them getting to file taxes jointly, or three of them getting to have a Somerville domestic partnership.

We also wondered how the law would handle multiple different relationships. Suppose Pat and Sam have a relationship, and Sam and Alex do as well. All three live together as a household, but Pat and Alex aren't partners. The ordinance lets them all have one domestic partnership together. Do they also have the option of registering two separate partnerships? It looks to us like they can: (2.502.c.3) might mean you can't be married to someone else already, but it doesn't say you can't have an existing domestic partnership. Later on (2.505.a) says "When the term 'spouse' or 'marriage' is used in other city ordinances, it shall be interpreted to include a domestic partner or partnership." Without the word "other", we think this would mean that one partnership counts as a marriage for (2.502.c.3). As it's written, we don't see anything precluding multiple simultaneous partnerships.

Municipal-level domestic partnership probably doesn't go as far as state or federal, but it does have important effects:

• Health insurance: City employees' partners are eligible for health insurance since "The City of Somerville shall afford persons in domestic partnerships all the same rights and privileges afforded to those who are married" (2-505.b).

• Co-living: Somerville prohibits more than four unrelated people from sharing a unit (9.11.a). Since "When the term 'spouse' or 'marriage' is used in other city ordinances, it shall be interpreted to include a domestic partner or partnership" (2-505.a), it looks to us like large households that consider themselves family can register as a domestic partnership and share a unit.

• Discrimination: "No person in our city shall be unlawfully discriminated against in matters of housing, employment, education, contracts, purchasing or public accommodations, on the basis of: age, ..., family/marital status, ..." (2.V.6.2.237). Before this, maybe a Somerville teacher could have been fired for coming out as living in a polyamorous family.

• Unlicensed peddling: "Before selling any meats, butter, cheese, fish, fresh fruit or vegetables, any hawker or peddler must either be duly licensed by the director of standards of the commonwealth or by the city council; however, this section shall not apply to any person who peddles only fish obtained by his or her own labor or his or her family's or to any person who peddles only fruits, vegetables or other farm products raised by himself or herself or his or her family" (8.IV.8.80).

That's just Somerville. Any other jurisdiction that recognizes Somerville domestic partnerships could also be affected!