Mayor Ralph Becker is defending against a second round of attacks on the legality of Salt Lake City's domestic-partnership registry.

And he's sticking up for its title, too.

Sen. Greg Bell, R-Fruit Heights, plans to introduce a bill that would set guidelines by which local governments can recognize unmarried couples as financial co-dependents without undermining Amendment 3, the state's constitutional amendment prohibiting same-sex marriage and other domestic unions.

Though text of Bell's bill was not yet available Tuesday, its expected intent is to force Salt Lake City to modify its domestic-partnership registry.

Proposed by Becker and approved Feb. 5 by the Salt Lake City Council, the registry provides a mechanism by which employers voluntarily can extend health care and other benefits to their employees' domestic partners — including same-sex relationships, siblings, long-term roommates and parents — if they reside in Salt Lake City.

Becker and members of the Salt Lake City Council have called the ordinance a natural progression from the February 2006 action that extended health benefits to adult designees of city employees.

"The primary substantive effect of the (domestic-partnership registry) is to make it easier for the private sector, for businesses and nonprofits, to look to a standard if they want to extend benefits to domestic partners," the mayor said.

Bell said he doesn't want to block those benefits. But it's important that those benefits aren't exclusive to same-sex couples so they don't violate Amendment 3 or lead to broader policies that could ultimately overturn the state constitutional ban on same-sex marriage and other domestic partnerships.

"We want to preserve the rights of a city or county to provide for employer-related domestic benefits to be shared on a neutral criteria," Bell said.

Becker contends that Salt Lake City's domestic-partnership registry already meets that neutral criteria because it's open to all people in relationships of mutual support, caring and commitment.

"It isn't defined in terms of same-sex or opposite-sex," he said. "It's defined in terms of the relationship between two people."

Though he said Salt Lake City's registry isn't necessarily in direct violation with Utah's gay marriage ban, Bell takes issue the term "domestic partnership." He said the term can be interpreted as "gay marriage light" because the registry is limited to couples who are co-habitating.

Becker said the city's own adult-designee ordinance belies that description because 78 percent of city employees who have utilized the provision are not same-sex couples.