Episcopal Bishop V. Gene Robinson also attended the bill signing. He and his longtime partner plan to take advantage of civil unions.
New Hampshire is the first state to embrace same-sex unions without a court order or the threat of one. Connecticut was the first to adopt civil unions without a court order two years ago. A lawsuit challenging the marriage law was pending, but legislators said they were not influenced by it.
Vermont, California, New Jersey, Maine, and Washington also have laws allowing either civil unions or domestic partnerships, and Oregon will join the list in January.
Hawaii extends certain spousal rights to same-sex couples and cohabiting heterosexual pairs. Only Massachusetts allows same-sex couples to marry.
Couples entering civil unions will have the same rights, responsibilities, and obligations as married couples. Same-sex unions from other states would be recognized if they were legal in the state where they were performed.
In a busy day at the State House, votes yesterday put New Hampshire on the path to join its New England neighbors in banning smoking in bars and restaurants, but to remain the only state without a mandatory seat belt law.
The state Senate voted 16 to 8 yesterday against requiring adults to buckle up.
"Today, you may hear that 49 other states have passed similar legislation," said Senator Bob Clegg, a Republican. "I happen to be proud of the fact that here in New Hampshire, we make our own decisions. If you want to wear a seat belt, you are free to do so. If you want to risk your life by not wearing one, it is not the government's responsibility to force you to."
But Senator Maggie Hassan, a Democrat, argued that the cost is too great. She said General John Stark, famous for the state's "Live Free or Die" motto, did not mean that people should do whatever they want.
"I ask if the words will mean the same to you from the seat of a wheelchair or to your family at your gravesite," she said.
Also yesterday, the House voted 224 to 117 to send a bill imposing the smoking ban to Lynch, who has said he will sign it. It will take effect 90 days later.
