The Virginia Senate, in what one lawmaker described as "a field day on lining our pockets," voted today to exempt legislators and local government officials from being tried on conflict-of-interest charges.

In the most bitter and dramatic debate of the 1986 General Assembly, the Senate voted 20 to 18 to weaken further an ethics bill that had been substantially diluted by the House.

"You're making this a place where we can all use our vote to get rich," shouted Sen. Joseph V. Gartlan Jr. (D-Fairfax), who made the remark about "lining our pockets." Gartlan led an unsuccessful fight to retain provisions of the law that allows the criminal prosecutions.

Today's action means that the assembly is certain to send Gov. Gerald L. Baliles legislation that he has called unnecessary. The governor, who supports the current law, has not said whether he would veto the weakened ethics measure.

"This places Virginia in the position of having one of the weakest conflict-of-interest laws in the nation," said Deborah Chalfie, legislative director of the Washington-based consumer lobby Help Abolish Legal Tyranny, which recently completed a nationwide survey of state ethics laws.

"Having no outside scrutiny turns it into a conflicts law that is really no law at all," she said. Her group appealed to Baliles today to veto the measure.

The Senate's three-hour debate, which at times resembled a theatrical performance, climaxed weeks of controversy over an issue that has consumed the current legislative session. For the first time, senators publicly chastised their colleagues for failing to take action against Sen. Peter K. Babalas (D-Norfolk), who is facing criminal charges of violating the conflicts law.

"Our conflicts act is less than three years old and is being applied for the first time in a criminal case now pending," said Gartlan, alluding to Babalas. "And we are being asked to junk one of its critically important parts."

Others argued that the assembly -- not the courts -- should police the conduct of Virginia's 140 legislators. "We should be able to look him a legislator in the eye and say, 'What you did is not up to the standards we operate by,' " said Sen. Dudley J. Emick Jr. (D-Botetourt) in an animated 40-minute speech attacking the current conflicts law.

Babalas, the fourth-ranking member of the Senate, was slumped in his chair with eyes lowered throughout most of the discussion and abstained from voting. A Norfolk lawyer, he faces trial May 20 on charges that he violated the conflicts law by voting last year to kill legislation that would have adversely affected second-mortgage companies, including one that paid him $61,000 in legal fees. Babalas has said he is innocent and will fight the charges.

The ethics measure approved by the Senate today would exempt lawmakers from criminal prosecution on similar charges. Instead, all disciplinary actions would be left to the discretion of the General Assembly. It has been reluctant to punish its members, most recently agreeing to await the outcome of Babalas' trial before considering disciplinary action.

Some lawmakers argued that criminal prosecution of legislators is unconstitutional. They argued that under Virginia's separation of powers between the legislative and judicial branches of government, lawmakers are immune from prosecution for actions taken in the course of legislative duties, even if they vote on issues in which they have a personal financial interest.

Critics argued that the House and Senate could not judge its members objectively. "At the most there might be a tap on the wrist," argued Sen. Clive L. DuVal II (D-Fairfax).

"If we pass this, the public will be appalled that we're so easily letting ourselves off the ethical hook," said Sen. Elliot S. Schewel (D-Lynchburg).

Under changes approved by the Senate today, local governing bodies could exempt their members from criminal prosecution if they establish internal ethics panels.

All Northern Virginia senators except John H. Chichester (R-Stafford) and Charles J. Colgan (D-Prince William) voted to oppose the weakened ethics bill.

The measure must go to a House-Senate conference committee for resolution of differences between the two chambers. Because many of the changes the Senate approved were drafted by a committee that met in secret that included House Speaker A.L. Philpott (D-Henry) and other House leaders, legislators predicted that the House will go along with most of the Senate bill.

Some said the House may not agree to exempt local government officials.

The proposed changes in the state's conflicts law began early in the session as an attempt to address a year-old state Supreme Court ruling that interpreted the existing law as barring legislators from voting on or discussing any legislative issue that could affect their profession or personal business.

Today's vote came as ethical questions were being raised about funds received by Sen. A. Joe Canada Jr. (R-Virginia Beach). He got a $5,000 campaign contribution last February from Landbank Equity Corp., the same second-mortgage company that paid Babalas $61,000, according to campaign finance reports.

In addition, Landbank gave Canada two mortgages totaling more than $118,000, and an affliliated company gave him a $15,000 check for "attorneys fees," the Norfolk Virginian-Pilot and Ledger-Star newspaper reported.

The payments and mortgages went to Canada as the General Assembly was considering the bill capping interest rates on second mortgages. It died in a committee, and Canada, now a congressional candidate, never voted on it.

Canada said there was no connection between the payments and the legislation and said he never dis- cussed the legislative matter with Landbank officials. He said it was a coincidence that the financial dealings with Landbank occurred at about the time that the legislature was considering the interest rate bill. Canada said the $15,000 payment was not for attorneys fees but was payment for a Cadillac he sold to a Landbank official.