BOSTON -- Dr. Peter Masiakos, was the trauma physician on duty at Massachusetts General Hospital on Oct. 22, 2006, the day 8-year-old Sean Kearney was brought in after suffering fatal injuries in a horrific ATV accident.

Masiakos, a pediatric, trauma and general surgeon from Sudbury, remained Kearney's doctor until he succumbed to his injuries five days later. An interest in the subject of ATV accidents involving children, however, started to weigh on his mind, he said.

Nearly four years later, through the efforts of Masiakos, Kearney's family and others, new legislation aims to keep tragedies like the Kearneys' from happening again.

Supporters hope that the bill, dubbed "Sean's Law" and signed by Gov. Deval Patrick on Saturday, will increase the safety of off-highway vehicle riding, most notably by raising the minimum age required to ride one of the vehicles from 10 to 14.

"This legislation has many public benefits –- improving rider safety, protecting private property and public land and safeguarding sensitive natural resources," Patrick said. "I want to thank our partners in the Legislature and in the private sector for helping us take these important steps in protecting our residents and our public spaces."

Sean's family was present at the signing. His mother, Katie Kearney, spoke about the importance of the bill and thanked legislators for their support.

"We are very thankful today for the signing of the ATV legislation, and are confident that Sean's law will save lives," she said. "We couldn't prevent what happened to Sean, but we believe this law will prevent any more children in the future from being hurt."

After Sean Kearney's death, Masiakos began researching prior laws enacted elsewhere that dealt with children riding ATVs. The main law that he noticed was one passed in Halifax, Nova Scotia, in 2006.

It restricted the operation of ATVs to only people age 14 and older. Drivers between the ages of 14 and 16 had to complete a safety class in order to operate an ATV. The year after the law was passed, ATV-related injuries in children younger than 14 experienced a 50 percent drop, Masiakos explained.

One year later, the Kearneys contacted Masiakos. They were attempting to build support for a similar bill raising the minimum age for a child to operate an OHV in Massachusetts.

Initially, he was asked to do some research for them regarding the medical community's stance on OHV-related injuries, in order to gauge support for an eventual lobby effort for the bill.

Eventually, he became a full advocate of the bill, actively writing state representatives and doing further research into outcomes of past laws.

Prior to the passing of "Sean's Law," the minimum age for a child to operate an OHV while supervised by an adult was 12. Children as young as 10 could ride an OHV if they were on the supervising adult's private property. Mandatory training is also now required for all OHV operators 18 years old and younger.

Citing the 19 OHV-related child fatalities in Massachusetts since 1982, and 143 in the United States in 2006 alone, Masiakos emphasized the inability of children to ride OHVs safely.

"They don't have the physical capability to ride them," he said, noting that many of the injuries occur as a result of the child losing control of the vehicle.

Referring to the Halifax law as an example, he expressed hope that Sean's Law will succeed in decreasing OHV-related injuries in children. He recognized, however, that seeing results may take some time, depending on how the law is implemented.

"It's our onus now to teach and to educate that it exists," he said.