Both sides in the no-holds-barred debate over no-fault automobile insurance in the District of Columbia insist that they are the true champions of the consumer.

The trial lawyers who triumphed yesterday over the insurance industry when the D.C. City Council voted to repeal the two-year-old mandatory no-fault law, argued that no-fault forced drivers to pay for insurance coverage that they already had or did not need; unfairly restricted their rights to sue those who caused their injuries, and resulted in neither lower rates nor quicker payment of claims.

The insurance companies, which lobbied heavily to retain the no-fault system, countered that it was working well and that the new law would mean less protection for drivers at much higher insurance premiums.

But D.C. insurance officials say it is impossible to predict what will happen to insurance rates as a result of the council's action.

A May 1985 study by the U.S. Department of Transportation concluded that insurance premiums in no-fault states tended to be higher, but found that drivers in no-fault states were twice as likely to recover funds for their injuries, were reimbursed more quickly, and received more money in claims for every dollar they spent in premiums.

Figures were not yet available for the District when the study was completed.

Under no-fault insurance, those injured in auto accidents collect from their own insurance companies regardless of who was at fault. While drivers will still be able to purchase no-fault coverage under the measure adopted yesterday, the only mandatory insurance will be traditional liability insurance under which accident victims collect from the person at fault.

Government Employees Insurance Company (GEICO), the District's largest autombile insurer, estimated that premiums for the minimum required coverage would rise an average of 11 percent, from $225 to $250.50. However, the company included in that figure a $20 cost for "medical bill" coverage that GEICO Vice President August P. Alegi conceded is not required under the law.

For those policyholders who want to continue to buy the current no-fault package on top of the liability insurance, GEICO estimated that rates would increase 25 percent to $282.20.

The District's second-largest auto insurer, State Farm, estimated that its average premiums for the compulsory coverage would rise 27 percent, from $160 to $203, and that the costs of compulsory insurance plus the existing no-fault package would jump 60 percent to $256.

D.C. Insurance Commissioner Margurite Stokes, whose boss, Mayor Marion Barry, proposed the change in the law, disputed the insurance companies' contention that rates would skyrocket.

However, Stokes said she did not have alternative estimates of the new law's effect on rates and did not know whether overall premiums had gone up, gone down or stayed the same after the switch to no-fault.

She said that the cost of the mandatory no-fault package has risen an average 8 percent -- and as much as 36 percent -- since the system went into effect Oct. 1, 1983.

GEICO's Alegi said the system was working as planned, with GEICO paying claims, on average, less than six days after they are submitted with supporting documents. During the first 18 months that the no-fault system was in place, according to GEICO figures, the company paid a total of nearly $6.2 million in claims, compared to $4.8 million during the previous 18 months.

"Now if you're in an accident you get paid immediately," Alegi said. "Under this [new] law, you're going to have to hire a lawyer, sue, and pay him one-third of what you collect."

But the city's personal injury lawyers, who found their practices hurt by the no-fault law's restriction on most lawsuits stemming from automobile accidents, accuse the insurance companies of stonewalling on paying many claims.

"There was no prompt and speedy payments," said Donald J. Chaikin, a leading personal injury lawyer here. He said his office is "rampant with claims" that insurance companies have failed to pay within the required 30-day period.

The lawyers also argue that the no-fault law did not make sense. Drivers who already had some form of health-care insurance, they said, were forced to pay for it again, while those who were retired or unemployed had to purchase wage insurance that they could not use.

"You're paying a premium for something you're probably never going to get the benefit of," said Edward L. Norwind, president of the Metropolitan Washington Trial Lawyers' Association.

The biggest problem with no-fault, the trial lawyers contend, is its restriction on victims' ability to recover the often substantial damages for "pain and suffering." Filing such suits, Chaikin said, is "a basic inherent right in this country."

A seven-member city commission studying the no-fault law was to report its findings by June 1987.

"It's presumptuous and premature to change the law," said James E. Jones Jr. of the Alliance of American Insurers. "Why the rush all of a sudden?"