OSTON, May 2 — A commission appointed by Gov. Mitt Romney has come up with what it considers the first virtually foolproof formula for carrying out the death penalty, and Mr. Romney is expected to use the plan to try to bring back capital punishment to the state, where it was abolished two decades ago.

One of the major recommendations is raising the bar for a death penalty sentence from the normal legal standard of guilt "beyond a reasonable doubt" to a finding of "no doubt about the defendant's guilt." The commission has also proposed that a defendant in a capital case be given the option of facing two separate juries: one for trial and, if convicted, a second for sentencing.

A co-chairman of the commission, Joseph L. Hoffmann, a law professor at Indiana University, said the idea was to avoid the contradiction that can arise when a defendant contests his guilt in the first phase of the trial, but in the sentencing phase, in order to get the lightest sentence possible, admits guilt and claims to be remorseful. The commission's 10 recommendations are intended to counter increasing skepticism about the death penalty.

"Taken as a whole, these 10 proposals would create a death penalty system for Massachusetts unlike any such system that has ever existed, or even seriously been considered before," the commission said in its report, which is scheduled to be released on Monday.

A spokeswoman for Mr. Romney, a Republican, said he would not comment on the report until it was released. Last September, when Mr. Romney appointed the commission, he said in an interview that he was "looking for a standard of certainty" to "assure us that only the guilty will suffer the death penalty."

The proposals, which the commission warned would be expensive, include several ideas that experts say are unprecedented, and others that have been tried but not so comprehensively. The plan is sure to be controversial, and even death penalty supporters said they had concerns about the viability of some of the ideas. On the other hand, even some death penalty opponents acknowledged that the plan would reduce the possibility of wrongful death sentences and racial disparities in sentencing.

The cornerstones of the commission's recommendations are that the death penalty be applied only to a narrow list of cases and that each case include scientific evidence, like DNA, fingerprints or footprints.

The death penalty would be sought only in the "worst of the worst" murders, the report said: torture murders, political terrorism murders, murders of police officers or others in the criminal justice system, and murders of multiple victims.

The physical evidence required would have to "strongly corroborate the defendant's guilt," connecting the defendant either to "the crime scene, the murder weapon or the victim's body." An independent board would review the scientific evidence.

In addition, the judge would be required to give the jury special warnings that nonscientific evidence, like testimony and witness identification, can be unreliable.

The commission also recommended that courts get broad authority to set aside wrongful death sentences, that the state attorney general review every decision by a district attorney to bring a capital case and that a separate review board investigate claims of errors in death penalty cases.

"There's no system that's remotely like this anywhere else," said Professor Hoffmann, who led the 11-member commission, which included prosecutors, police officials, forensic scientists and a retired judge. "The death penalty ought to be reserved for only the most clear-cut, sure-thing cases."

One expert, Jamie Orenstein, a former Justice Department official who worked on the death penalty prosecution of Timothy J. McVeigh in the Oklahoma City bombing, said the recommendations were indeed innovative, but ran the risk of making the criteria so narrow that "no one is going to be executed under this law."

"They really seem to be making an effort to have a less bad death penalty, but in doing that they just show how that's an impossible thing," Mr. Orenstein said. "With all the restrictions you need, you wind up distorting your system."

Massachusetts is one of 12 states without capital punishment, which was banned there in 1984 and last used in 1947. Since 1991, a series of Republican governors have tried to reinstate the death penalty. They came closest in 1997 after the rape and murder of a 10-year-old boy, when a tie in the Massachusetts House of Representatives defeated a capital punishment bill.

In recent years, sentiment against capital punishment has increased, with a bill in 2001 losing by 34 votes in the House. But late last year, federal jurors in Boston sentenced Gary Sampson to death for killing two men during a weeklong rampage three years ago. And in November, a poll by the University of Massachusetts found that 54 percent wanted the death penalty reinstated and 45 percent did not. Sixty-two percent said they were skeptical that Mr. Romney could establish a flawless system.

The most powerful Democrat in the legislature, Thomas M. Finneran, the speaker of the House, is not morally opposed to capital punishment, but is wary of wrongful convictions, said a spokesman, Charles Rasmussen. He said that Mr. Finneran was "open to the findings" of the commission. Mr. Romney is expected to use the capital punishment issue to try to elect more Republican legislators this year.

Death penalty supporters said the reliance on scientific evidence would lead to few capital cases. "In the vast majority of murder cases you're not going to have that kind of evidence," said Joshua Marquis, a pro-death penalty district attorney for Clatsop County, Ore., and co-chairman of the National District Attorneys Association's capital litigation committee.

Mr. Marquis and other experts also said that requiring a standard of "no doubt" at the sentencing phase would sharply limit the possibility of a death sentence.

"You're going to have a lot of people who say I'm not 100 percent certain about anything," Mr. Marquis said.

Death penalty opponents like Elisabeth Semel, director of the Death Penalty Clinic at the University of California, Berkeley law school, said the scientific requirements would help "reduce the likelihood of wrongful capital convictions." "But it's kind of like using seat belts," she said. "If you use the seat belt, you reduce the chance of a fatality, but using a seat belt does not prevent accidents."

David M. Ehrmann, chairman and president of Massachusetts Citizens Against the Death Penalty, and the grandson of the lawyer who defended Nicola Sacco and Bartolomeo Vanzetti, said the system "will have safeguards; it will wear a white lab coat." "But all human systems by definition can have errors in them, regardless of safeguards," he said.

Mr. Orenstein, the former Justice official, said the two-jury proposal could introduce more "arbitrariness" into the process, and other proposals could make for counterintuitive outcomes: for example, if there were two co-defendants and the one with enough evidence against him to merit the death penalty had a smaller role in the crime.

But he said that by excluding certain crimes like robbery-murders, the recommendations would eliminate most racial bias in capital cases.