A Maryland House committee that has repeatedly killed mandatory seat belt legislation shocked and delighted many lawmakers today when its members approved such a bill and sent it to the full House.

Turning aside longstanding arguments from its powerful chairman that the bill would serve no purpose but unwarranted government meddling into private affairs, the House Judiciary Committee voted 12 to 9 to require drivers and passengers in the front seats of cars to wear seat belts. Committee approval had been viewed as the main hurdle to passage of a mandatory seat belt law, and supporters of the measure were hopeful of passage by the full House.

The full Senate has already passed a seat belt law, so if the measure is approved by the full House and both bodies agree on the final wording, Maryland would join 18 other states and the District of Columbia in requiring automobile drivers and passengers to use the restraining devices, said a spokeswoman for the Potomac chapter of the American Automobile Association.

The action came on a day when the Maryland legislature sharply escalated its pace of activity with three weeks left in the session and advanced several of the session's most controversial bills.

The Senate also voted to authorize several new housing programs proposed by Gov. Harry Hughes. But much of the activity took place in committees of the House of Delegates, which has lagged behind the Senate in moving key legislation this year. One committee also gave its approval to Hughes' housing programs, and another engaged in intensive negotiations over another controversial issue, a measure that would impose sharp restrictions on shoreline development in an effort to clean up the Chesapeake Bay.

But the most surprising development was the approval of the seat belt bill, which advocates and opponents had been lobbying from the beginning of the session.

The bill would allow police officers to charge drivers with failing to comply with the seat belt law only if they are already charged with another offense, a provision also carried by the Senate bill. The charge would be a moving violation and cost motorists a "point" on their records. Under the House bill, the fine would be $25, and $20 under the Senate bill.

Mary Anne Reynolds of AAA, among the groups lobbying for the measure, called the committee vote "super."

"Nothing has thrilled us more," said Agnes Beaton, director of the National Coalition of Women Highway Safety Leaders.

A proposal to make wearing seat belts mandatory in Virginia died on the next to last day of the legislative session early this month. The bill, which had passed the House, was killed in the Senate when Lt. Gov. L. Douglas Wilder broke a tie vote and then refused to allow one member, who said his vote was in error, to change his vote.

The Maryland mandatory seat belt bill died in the Judiciary Committee last year on a resounding 14-to-4 vote.

Today's vote in the Judiciary Committee came almost two months after the full Senate passed the measure. Approval came after an early morning debate over amendments intended alternately to strengthen and weaken the bill, a discussion that left committee members accusing each other of trying to kill the measure and confused about its final effect.

Rejected by the House panel on a series of close votes that characterized the session were amendments by Prince George's Democratic Dels. Joseph Vallario and Richard Palumbo that would have exempted newspaper carriers, mail carriers, police officers and those in their custody from provisions of the bill.

Another Vallario amendment adopted by the panel is directed at one of the peculiarities of Maryland law -- a provision that if a person contributes in any way to his or her own injury, he or she may not collect damages in a lawsuit. Under the amendment a driver or passenger who is not wearing a seat belt cannot be charged with contributing to his own injury in the event of a lawsuit. Before winning approval, that language sparked some of today's most heated discussion.

Opponent Joseph Owens (D-Montgomery), who as chairman of the panel did not vote, said, "It's a mishmash really. What they're trying to do is make it so it doesn't hurt anybody but it doesn't have any effect."

But supporters, like bill sponsor Arthur Alperstein (D-Baltimore County), argued that the amendments would make the bill easier to pass. "It's obvious to me that if you kill all these amendments you've got a very difficult bill for the House to accept," he said.

Approval of the measure came after weeks of intensive lobbying on the part of bill sponsors and other supporters that was required to persuade a third of the previous opponents to change their votes. Among those who were persuaded was Vallario, who said he has "never used a seat belt in my life."

This year, he said, he was convinced by testimony from medical professionals. "Something they said just rang in my mind, that we could save some lives by the stroke of a pen. I didn't hear that last year."

Del. Jerry Hyatt (D-Montgomery), who voted against the measure although he said he favors seat belts for his own use, called the measure an unwarranted intrusion into personal affairs. But he said the committee was "bombarded" by lobbying groups funded by auto manufacturers, who favor mandatory seat belt laws as a way to escape proposed federal regulations that would compel them to install air bags in cars.

The Maryland Committee for Safety Belt Use, partially funded by auto manufacturers and dealers, has spent $200,000 on the effort this year, its director said.

In other action, the Senate approved a $38 million package of measures intended to improve housing opportunities for the state's low-income residents. The package, also approved today by the House Ways and Means Committee, would allow state funds to be used to produce housing for low-income families, install indoor plumbing, subsidize housing for disabled adults and pay for closing costs for low-income buyers.

The programs had been proposed by Gov. Hughes as part of a comprehensive housing initiative that has so far won broad support in the legislature. Nevertheless, the Ways and Means Committee, brushing aside the pleas of social service advocates and administration officials, also voted today to kill a key part of the package, a program to subsidize rental costs for low-income adults.

In a dramatic vote, the committee split 11 to 11 on whether to cut the funds, with Chairman Tyras (Bunk) Athey (D-Anne Arundel), breaking the tie to cut the funds.

The same panel also upheld a subcommittee decision to weaken substantially a proposed statewide housing code.

The original proposal set minimum "livability" standards, which local governments would have to equal or exceed. A Senate panel retained the concept of minimum statewide standards but voted to delay implementation until 1988, and the full Senate resisted efforts to weaken the standards in a preliminary vote today.

But the Ways and Means Committee voted, in a move that puts them in conflict with the Senate, to delay full implementation until 1989, and to require that local governments draft and enforce their own housing codes. They deleted any minimum standards, except for jurisdictions that fail to implement their own codes by the target date.

Eastern Shore lawmakers had opposed the code entirely as an intrusion into local decision-making.

"There ought to be flexibility. That which is appropriate for Montgomery and Howard County may not be applicable to the Eastern Shore," said Del. Daniel Long (D-Eastern Shore). "I'm not sure the state ought to be in the business of dictating to the local governments, particularly when there's going to be local enforcement."

Eastern Shore lawmakers' resentment of what they viewed as state government interference boiled over into another controversy today, involving Chesapeake Bay cleanup efforts. On Saturday, a House Environmental Matters work group voted to approve legislation sought by Eastern Shore lawmakers that would significantly weaken measures to limit development along the bay shoreline. The full committee was scheduled to vote on the legislation today but that vote was delayed as House leaders tried to negotiate a compromise.

Here is a list of House Judiciary Committee members who voted for the mandatory seat belt bill:

Pauline Menes (D-Prince George's), Mary Adams (D-Baltimore), Joseph Vallario (D-Prince George's), Jerry Perry (D-Prince George's), Joel Chasnoff (D-Montgomery), John Leopold (R-Anne Arundel), Arthur Alperstein (D-Baltimore County), Elmer Hagner (D-Anne Arundel), Thomas Rymer (D-Calvert-St. Mary's), Richard Palumbo (D-Prince George's), Elijah Cummings (D-Baltimore), Anne Perkins (D-Baltimore).

Members voting against the seat belt bill:

Ralph Hughes (D-Baltimore), Richard Matthews (R-Carroll), Jerry Hyatt (D-Montgomery), William Horne (D-Eastern Shore), W. Lanny Harchenhorn (R-Carroll), M. Albert Morningstar (D-Frederick), Kenneth Masters (D-Baltimore County), Joseph Bartenfelder (D-Baltimore County), William Byrnes (D-Western Maryland).