Better buckle up.

That was the message from the Massachusetts Senate as it approved a bill Thursday giving police the ability to pull over drivers and cite them solely for not using seat belts.

Current state law allows police to cite drivers for not buckling up only if they pull them over for some other reason first.

Supporters of the so-called "primary seat belt" bill say it will save dozens of lives and spare hundreds from dire injuries. Opponents argue it will increase the power of the state and erode the civil rights of minority drivers.

Susan Monack of Milton lost her 19-year-old son Gregory when he fell asleep at the wheel of his car and crashed into a tree three years ago after working all day and visiting friends. He was not wearing a seat belt and had just finished his freshman year at Boston College.

"This is wonderful today. This is what we have worked for," said Monack, clutching a photo of her son outside the Senate chambers. "I wish they had it five or 10 years ago, but at least they'll have it now."

The 24-15 vote in the Senate comes after House lawmakers approved the bill in January by a 76-74 vote, the narrowest of margins possible. It followed two deadlocked House votes in 2001 and 2003.

Gov. Mitt Romney has said he supports it.

Sen. Mark Montigny, D-New Bedford, said the bill is about clarifying the existing seat belt law and sparing families the agony of hearing that their child or loved one had been killed or grievously injured because they weren't wearing a seat belt.

"This is about saving lives," Montigny said. "Let's stop the wink, wink, smile, smile and give a very direct instruction to the police."

Others feared an expansion of police powers.

Sen. Jarrett Barrios, D-Cambridge, said he supports the use of seat belts but argued the bill could open the door to racial profiling by police.

"The good intention of saving lives impacts some of us more than others," Barrios said. "Some of us know from our life experience that this law will not always make our lives safer."

Sen. Andrea Nuciforo Jr., D-Pittsfield, said the bill would lead to more intrusive traffic stops by police.

"We have an obligation under the constitution to protect our citizens from unreasonable interference from the government," he said.

The number of Massachusetts drivers who buckle up has risen over the past five years, but the state still ranks near the bottom of seat belt usage nationally. Twenty-two other states have "primary" seat belt laws.

In 2000, 50 percent of Massachusetts drivers and passengers wore seat belts, compared to 64.8 percent last year, according to National Highway Traffic Safety Administration statistics. Nationally, seat belt use overall was a record 82 percent in 2005.

Critics of the bill proposed an amendment that would have kept the secondary enforcement law but increased fines for not wearing seat belts from $25 to $200 and would have held drivers responsible by fining them for everyone in the car who was not buckled up.

The amendment, which was defeated, also proposed 45-day drivers license suspensions for teens not using seat belts.

Sen. Dianne Wilkerson, D-Boston, said the higher fines and suspensions would be more of an incentive for using safety restraints than a primary seat belt law.