On the warm, dry, and cloudless afternoon of Wednesday, May 25, at about 1 p.m., Robert B. Sparrow was riding north on Kelly Drive with a woman passenger, her arms wrapped around him on a 2004 Suzuki motorcycle.

At Breweryhill Road, Sparrow tried to turn right and hit a Mercedes-Benz traveling in the same direction to his left. Sparrow's motorcycle struck a stone embankment.

He died instantly. He was 36 years old.

His 25-year-old passenger was taken to Hahnemann University Hospital in critical condition.

Neither was wearing a helmet.

There are those who would argue that because the Pennsylvania legislature refuses to require all motorcyclists to wear protective headgear, it is complicit in these tragedies.

For decades, the state had a mandatory helmet law. But in 2003, on Gov. Ed Rendell's watch, it was repealed.

Ever since, the majority of the state's legislators has steadfastly upheld the principle of "liberty above all."

And ever since, State Rep. Dan Frankel (D., Allegheny) has been trying to persuade them to reinstate the helmet requirement.

At the end of May, he introduced yet another bill to revive the law - his fourth attempt. "I do it every session," Frankel says. "But I know it won't go anywhere."

The law, he says, is widely viewed as a commonsense public health measure.

"There is an alternative to reading these stories about fatalities and brain injuries."

Research by universities, public policy centers, epidemiologists, neurologists, orthopedic surgeons, and government agencies has come to the same conclusion.

Helmets save lives and reduce suffering.

One study at the Johns Hopkins University School of Medicine looked at more than 40,000 motorcycle collisions between 2002 and 2006 and found that motorcyclists who wore helmets were 65 percent less likely to suffer traumatic brain injury, 22 percent less likely to suffer cervical spine injury, and 37 percent less likely to die than riders without helmets. "But single-interest groups like the bikers hold a lot of sway over lawmakers," Frankel says.

The motorcycle group ABATE (A Brotherhood Aimed Towards Education of Pennsylvania) and its political action committee, Bike PAC, have lobbied long and hard to win and maintain what members say is their freedom of choice. Like smoking cigarettes or eating fried food, they argue, riding one's chopper without a helmet is a personal decision, and no paternalistic government agency has the right to interfere.

Records provided by the National Institute on Money in State Politics show that the bikers' group contributed more than $72,000 to state legislators in 2010.

When Frankel reintroduced his legislation May 23, he brought reinforcements, including a high-ranking official from the National Transportation Safety Board, nursing and trauma specialists, and Kristen Mertz, an epidemiologist from the University of Pittsburgh who cowrote a 2008 study on the rise of deaths and injuries after the helmet law was repealed.

In response, one of ABATE's main lobbyists, Charles Umbenhauer, posted this warning on the group's website:

"Prompted in part by the state's budget deficit, Frankel also plans to introduce legislation to require additional insurance for motorcycle riders who choose not to wear a helmet. He also will introduce a bill to provide for special motorcycle license plates for riders under the age of 21.

"This is a serious threat to our freedom. Don't take it lightly. The Legislature is in the process of doing the state budget, and Frankel is trying to make a case that bikers are costing the taxpayers millions of dollars in unnecessary medical bills. He claims we can reduce all of these medical costs if a universal helmet law is reenacted to cover all motorcyclists in the commonwealth. Don't think for one minute that this guy isn't dead serious about making an honest effort to put a helmet back on every head."

Umbenhauer urged all members to rally to the Capitol and protest loudly (but politely).

"Fail to answer the call and we play right into Frankel's web of deceit. A lot of years of hard work, not to mention big bucks, went into securing your freedom of choice."

Meanwhile, the public has been laying out some pretty big bucks, too, says Frankel.

"Hospitalization costs resulting from motorcycle accidents cost the commonwealth $18 million a year. Disability and long-term care are $55 million," says Frankel.

Calculating the emotional costs to victims and their families is a lot harder. It's the principle, though, that drives the bikers.

Contact staff writer Melissa Dribben at 215-854-2590 or mdribben@phillynews.com.