A person injured in a car crash is treated in the emergency room. The insurance company pays the out-of-network doctors involved in the care less than they think they're owed.

So a doctor or the hospital sends a bill for the remainder directly to the patient.

It's called "balance billing" and has spawned a turf battle among state officials who are trying to outlaw the practice, insurers who support the ban and doctors who fight it and see themselves as victims.

"Legislate, regulate and litigate. We'll do whatever it takes," said California Medical Association President Richard Frankenstein, before a meeting with Ventura County doctors this week. He laid responsibility for balance billing on insurers trying to protect their profits by underpaying doctors.

"It's a very clever ploy of multimillion-dollar companies to avoid their responsibilities," he said.

But some patient advocates say there's enough blame to share. They say the fight over compensation for emergency care ends up wounding patients who worry that if they don't pay the doctor's bill, their account will end up with a collection agency.

"We're caught between these two institutional providers," said Beth Capell, an advocate with Health Access California. "It's a temptation to say a plague on both your houses."

Many of the problems occur in emergency rooms where neither patients nor doctors control who they see. People may be treated by providers who don't contract with their insurance company. The doctors are paid a lesser, out-of-network rate.

According to the California Association of Health Plans, 1.76 million Californians who went to emergency rooms over a two-year period were billed by doctors or hospitals for money not paid by insurers.

The total bill was about $528 million.

The California Department of Managed Health Care plans to roll out a regulation next month that labels balance billing for emergency care as an unfair practice, opening the door to enforcement action against doctors or hospitals.

A bill by Sen. Don Perata, D-Oakland, would ban ER doctors from balance billing and would set up a process to mediate insurance disputes as well as an interim rate of payment. The bill was approved by the Legislature two weeks ago and awaits Gov. Arnold Schwarzenegger's signature. It would supersede the managed care regulation.

The doctors' association will sue the day after the state implements its new rules, said Frankenstein, in Camarillo for a meeting of the Ventura County Medical Association. The state group also opposes Perata's bill, though a group of emergency physicians supports the measure.

Frankenstein said insurance companies need to expand their networks to include more emergency room and on-call doctors. They also need to pay more, he said.

"It's up to the health plan to either serve up the doctor or pay the bill," Frankenstein said, suggesting insurers maximize profit by saying, "This is what we feel like paying today."

Nicole Kasabian Evans of the California Association of Health Plans fired back.

"Health plans are not the ones that are sending the bill to the consumer," she said. "We don't think it's appropriate strategy to hold patients hostage."

Evans said the insurance group supports a ban on balance billing and an independent process to deal with disputes with doctors. But the group opposes Perata's bill because the rate of payment may be too high. Doctors who currently contract with insurance companies might drop out to get the out-of-network rate, she said.

Eliminating balance billing is great if it comes with reform that transforms the healthcare system and provides insurance coverage to everyone, said Jim Lott, executive vice president of the Hospital Association of Southern California. But hospitals aren't happy about measures that eliminate the bills but not the underlying causes, he said.

"Balance billing is a tool hospitals use to force health plans into negotiating fair rates," he said. "Consumers need to know. If their health plan is screwing up, they need to know that."

Patients shouldn't be seen as a tool, said Cindy Ehnes, director of the state Department of Managed Health Care.

"It's inappropriate to put a vulnerable, potential sick patient in the middle of a billing dispute just to provide leverage," said Ehnes, calling on doctors to take their disputes to her department.

Local doctors say balance billing isn't about getting rich but about staying in business. Some predict that eliminating the mechanism will amplify other healthcare problems such as getting doctors to serve on call.

"I think that will be the death knell to taking call in the emergency room," said Dr. Mark Ghilarducci of Oxnard.

Jerry Flanagan of the Consumer Watchdog group in Santa Monica feels sympathy for doctors who can't break what he called the stranglehold of insurance. But he also blames the medical association for holding up years of efforts to end balance billing.

"As sympathetic as we are for the physician, we think there is no excuse for billing the patient because of disputes between the doctor and the insurance company," he said. Referring to strategies that would solve the problem, he said: "That's what we've been waiting five years for."