BURLINGTON, Vt. - An expert on smoking and health says R.J. Reynolds relied on suspect data to support its claim that smokers of its Eclipse cigarettes may face less risk than smokers of conventional brands.

Dr. David Burns is a pulmonologist and professor emeritus at the University of California-San Diego medical school. Testifying in a lawsuit, he said too few people took part in studies of the cigarette, and they didn't use it long enough for scientists to draw meaningful conclusions about whether it's safer than other brands.

Wyoming and 36 other states are suing the tobacco giant over what the lawsuit says were misleading claims that the Eclipse may carry less risk of cancer and other health ailments.

The suit says Reynolds violated consumer fraud laws in its marketing of the cigarette and seeks a court order barring the Winston-Salem, N.C., company from making the claims.

Reynolds contends that smokers' risk of cancer, chronic bronchitis and possibly emphysema are reduced with Eclipse because the cigarettes heat the tobacco without burning it.

"We believe the claims we have made regarding the product have been supported by credible and reliable scientific data," said Thomas McKim, vice president and deputy general counsel, in an interview outside the Chittenden County Superior Court courtroom where the case is being heard.

Burns, called as an expert witness by the plaintiff states, testified for a second day about Reynolds studies that the company says provide adequate scientific foundation for the advertising claims.

The trial is expected to last a month.

R.J. Reynolds plans to call about 13 witnesses, including company scientists and outside experts who will vouch for the credibility of the studies, according to McKim.

Vermont Assistant Attorney General Julie Brill, one of the states' lawyers in the case, said no judge had ever had to decide the question posed by the case.

"It's a huge question as to how much science or proof there should be before they can make a claim to consumers," she said.

The other states involved in the case are: Alaska, Arizona, Arkansas, California, Connecticut, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kentucky, Louisiana, Maine, Maryland, Michigan, Missouri, Monatna, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Utah, Vewrmont, Washington and Wisconsin.