The Florida legislature approved a bill yesterday ordering a rollback of commercial liability insurance rates of 40 percent or more -- to levels of January 1984, before premiums began soaring.

The measure also sets a $450,000 ceiling on non-economic liability awards such as "pain and suffering." It puts a $25,000 limit on "joint and several liability" so that a single defendant with "deep pockets" who is minimally at fault -- often a municipality -- can no longer be required to pay the entire jury award if the other defendants are insolvent.

This is the first time in more than 15 years that any state has legislated a rollback on insurance rates, according to Charles C. Clarke, executive vice president of the Insurance Information Institute in New York. The last time states mandated rate decreases was in the late 1960s and early 1970s when no-fault automobile insurance was introduced.

A half-dozen other states have set limits on non-economic awards, while another half dozen have pending legislation.

Florida is the only state so far to accompany liability award limits with a rate rollback.

The Reagan administration has introduced bills to hold such damage awards to $100,000 in liability suits against the federal government. But the Senate Commerce Committee was considering a substitute bill last week to raise that to $250,000.

The Florida legislation will mean lower rates for consumers, but it could cause a crisis for the industry. Insurance stocks have been battered because the rollback follows a Florida Supreme Court decision last week striking down a state law that prohibited insurance agents from rebating part of their commissions to customers. Since other states have similar laws, they also may face challenges.

Already Baltimore-based U.S. Fidelity & Guaranty Co. and Aetna have announced that they will not write new commercial policies in Florida. Other companies are expected to follow suit. Florida insurance commissioner Bill Gunter has discussed setting up a state-run insurance corporation for businesses unable to obtain coverage elsewhere.

Florida House and Senate conferees voted to freeze rates on commercial, property and liability lines for three months starting July 1. Between Oct. 1 and Dec. 31, there would be a 40 percent rate rollback for new and renewed policies or a refund for nonrenewals.

As of Oct. 1, insurance companies would have to file their 1987 rates based on rates in effect on Jan. 1, 1984. Gunter, who receives additional powers under the law, would have to decide whether a company's post-1984 loss experience warrants an increase from that base.

The more controversial liability-limit provisions were not resolved until the last minute, and the bill passed the House and Senate and was sent to Gov. Bob Graham (D) just before the session ended at 3 a.m. yesterday. Graham has indicated he supports the bill.

The $450,000 ceiling on non-economic damages was a compromise between the Senate's request for a $500,000 limit and the House's call for a $350,000 cap. If punitive damages are awarded, 60 percent would go to the state to pay for indigent health care in personal injury cases.

Rollbacks resulted from complaints by condominium owners about increases in early 1985. Liquor stores and day care centers also complained. A study conducted by a Florida industry group estimated that the average premium for commercial property and liability insurance rose 265 percent in that period. Florida ranks third in the total number of multimillion-dollar awards, according to Jury Verdict Research Inc. in Ohio.