Buckle up or you might be fined $25 under a new Massachusetts law that came into effect Tuesday.

The law, which requires everyone over the age of twelve to wear a seat belt, passed last month despite a veto by Governor William F. Weld '66.

"[The seat belt law] is not an abstract philosophical issue. It's about keeping human beings safe," said State Sen. Michael J. Barrett '70 (D-Cambridge), chair of the health care committee. "[Weld] let his libertarian ideas get in the way of common sense. The seat belt law will save lives and money."

The mandatory seat belt laws was first enacted in 1986. State Rep. Barbara Gray (D-Framingham), citing a study by the Boston University School of Public Health, said that during that year motor vehicle injuries decreased by 18,000 from 1985. But he law was repealed in a referendum a year later.

Since then the bill for mandatory seat belt law has drawn many new supporters, including Barrett and State Rep. Paul Caron (D-Spring-field).

"For every serious motor vehicle injury prevented, $35,000 is saved in health care costs," Barrett said.

Caron changed his stance on the seat belt law after it saved his life in a car accident. Gray, the law's original sponsor, attributes much of the bill's support to Caron.

But Weld and other politicians still disagree with the new law.

"I'm opposed to it," said City Councillor William H. Walsh. "[People should] wear a seat belt for safety, not because the government tells them to."

Walsh said he fears this new law may become a "revenue generator." like parking tickets.

"It's not helpful if the police are going to just go out and find people without seat belts to fine," he said.

The $25 fine can only be imposed after a driver has been stopped for some other offense.

Weld was unavailable for comment.