A federal jury handed Merck & Co. (MRK) a major victory when it cleared the drug maker of any responsibility in the death of a 53-year-old Florida man who had a heart attack after taking its once popular painkiller Vioxx for less than a month.

This was the second court victory for Merck, and the first in a federal court. The company had argued in this case that plaintiff lawyers never proved any link between Vioxx and the heart attack Richard "Dickey" Irvin suffered in 2001. Merck's lawyers contended Irvin's age, gender and diet all put him at risk for heart attacks

It was also the second time jurors heard the case brought by Irvin's family. In Houston, where the case was heard in November and December because of damage from Hurricane Katrina, jurors were unable to reach a verdict. Merck won a state case in New Jersey last year while it lost one in Texas.

Irvin's widow, Evelyn Irvin Plunkett; the youngest of their three daughters, Ashley Irvin; and their only son, Richard Irvin III, all testified that Irvin's health had been excellent up to his heart attack.

Irvin took Vioxx for back pain, but never saw a doctor about it. Instead, the resident of St. Augustine, Fla., called his son-in-law, an emergency room physician who lived in another city. He hadn't been able to keep down the first two painkillers Dr. Richard Schirmer prescribed; after he tried a sample given to him by an acquaintance, he asked Schirmer for Vioxx.

Schirmer testified that if the label had included a warning about heart attack risk, he wouldn't have prescribed Vioxx for his father-in-law.

Much of the evidence put on by Plunkett's attorneys focused on whether Merck should have added a warning to the label after it learned in early 2000 that patients taking Vioxx in a drug test called VIGOR had five times as many heart attacks as those on naproxen, another painkiller.

Jurors had to decide three questions about whether Merck did something wrong, and whether that action probably contributed to Irvin's death. Was Merck negligent? Did it fail to warn Schirmer about the drug's potential dangers? Was the drug unreasonably dangerous because of defective design?

They didn't have to agree that Vioxx definitely caused the heart attack in May 2001, or that it was the only possible cause, only that it is "more likely true than not true" that it was among the causes, U.S. District Judge Eldon Fallon told jurors.

"Our burden of proof is to show more likely than not. Fifty-one percent. More likely than not to show his heart attack was caused by Vioxx," Andy Birchfield, who represents Plunkett, told the jury during his closing argument.

He noted epidemiologist Wayne Ray's testimony that the drug probably was to blame for 54 percent of all heart attacks among people who suffered them while taking Vioxx. In Irvin's case, he said, that meant a 54 percent chance that the drug was among reasons for the heart attack.

Plunkett said she could not comment. "Not yet. I wish we could," she said.

Merck learned of the VIGOR study results in 2000. Had it stopped selling Vioxx or put a warning label on the drug then, he said, Irvin's son-in-law, an emergency room physician, would not have prescribed Vioxx for Irvin in April 2001.

"Did they rein in their massive marketing campaign? ... No. They pushed on wide open," he said. And he quoted the comment of Dr. Eric Topol, a cardiologist subpoenaed for videotaped testimony while at the Cleveland Clinic.

"He said that was human experimentation," Birchfield continued. "Merck was playing Russian roulette for money with Dickie Irvin."

Merck attorney Phil Beck countered that no physician testified that Vioxx caused Irvin's death. "In fact, no doctor testified that Vioxx was even a small factor in Mr. Irvin's heart attack and death."

In 2000, when VIGOR was published in the New England Journal of Medicine, Merck said the difference in outcomes among patients taking Vioxx and those on naproxen was probably because naproxen protected the heart. It said it immediately reported the data to the U.S. Food and Drug Administration.

The fact that it reported lower numbers to the New England Journal of Medicine than it did to the FDA was the subject of testimony by the journal's executive editor, Dr. Gregory Curfman. "The company wanted to keep the journal article pristine for the purposes of marketing. And it worked — for a while," Curfman said in a videotaped deposition.

Merck said the data reported to the journal occurred before a cutoff date set when a safety monitoring board for the study asked for analysis of cardiovascular side effects. Curfman said the journal should have been updated.

The case could be the first indication of outcomes in federal court, generally seen as more disciplined and friendly to businesses than state courts.

As of the end of December, Merck faced more than 9,600 state and federal lawsuits.

Fallon has been assigned to handle pretrial matters for all 4,000-plus federal cases, and has told attorneys he hopes to work out a settlement after the first four are tried.