Same-sex couples who are allowed to enter into civil unions would spend as much as $9.5 million on celebrations over the first four years of the new law, according to a new study.

The analysis of House Bill 444, which is awaiting a decision by Gov. Linda Lingle, was released Monday by the Williams Institute on Sexual Orientation Law and Public Policy at UCLA.

Opponents of HB 444 questioned the research and its methods, calling the study misleading and inaccurate.

The measure would grant all the rights, benefits, protections and privileges of traditional marriage to couples — regardless of gender — who enter into a civil union. Opponents say the bill is flawed and amounts to same-sex marriage.

Williams Institute researchers said their study was consistent with a similar analysis of HB 444 done by the University of Hawaii. It says more than 20 studies over the past decade by state governments and the Congressional Budget Office suggest HB 444 would have positive fiscal effects with minimal cost of implementation.

According to the Williams Institute study, 272 same-sex couples could be expected to enter into civil unions in the first years, with that figure increasing to as many as 1,285 over four years.

Estimated spending on celebrations by those couples would be between $4.2 million and $9.5 million in the first four years, while their guests would add an estimated $17.8 million to $40.3 million on hotels, food, retail and entertainment over four years, the study said.

Meanwhile, based on the experiences of states that have implemented civil unions, including Connecticut and New Jersey, costs for implementing the measure would be minimal, the study said.

"In addition to vital legal protections that HB 444 provides to all of Hawaii’s families, once again, another study shows that civil unions would have a positive impact on Hawaii’s economy, provide long-term financial benefits to the state, and attract new businesses and a skilled labor force," said Alan Spector, legislative co-chairman for Equality Hawaii.

Dennis Arakaki, executive director of the Hawaii Family Forum, said the organization requested comment from Moheb Ghali, vice provost for research and dean of the graduate school at Western Washington University, because of his background on economic issues.

"This is not a serious scholarly study," Ghali, an economics professor and former director of research at UH, said in an e-mail response. "Its claims are misleading, its references are inaccurate and as such I would not spend much time considering it."

Ghali said the analysis references only one academic study that addressed the fiscal impact of the bill, while other studies cited in the report were done by a combination of the same authors of the Williams Institute report. Only the 2004 Congressional Budget Office study could be considered independent, he added.

"Claiming over 20 studies by academic institutions, governments and trade industry associations is at best misleading," Ghali said.

Lingle, who is traveling in Asia, has said she would decide on the bill after she returns this week. She has until Monday to inform the Legislature of her intent.