The largest health insurance company in Texas is being closely watched by consumer watchdogs and hospital trade groups in Texas and across the U.S. as it prepares to crack down on overuse of costly emergency care services.

Starting in June, about 500,000 Blue Cross and Blue Shield of Texas members with HMO policies — which require the use of in-network doctors except in emergencies — will need to think twice before going to an out-of-network emergency room.

If it is later determined that a health problem wasn't serious enough to warrant emergency attention, the patient could be left on the hook for the entire medical bill. The Dallas Morning News detailed the coming change last week.

Blue Cross said it would share details on the change through benefit booklets and letters it will begin sending this week to HMO customers who used out-of-network emergency rooms last year. It was not immediately known if details would be posted on the SmartER website set up to help patients decide when to visit an emergency room.

Few dispute that more needs to be done to direct patients to lower-cost primary and urgent care clinics when appropriate.

“We all want to strive to get better health, better care and better value. There’s no question about it,” said W. Stephen Love, president and CEO of the Dallas-Fort Worth Hospital Council.

There’s far less agreement about whether the approach being taken by Blue Cross of Texas and a handful of other major U.S. health insurers is the right way to go about it.

“It’s like using an atomic bomb on a cockroach problem,” said Betsy Imholz, director of special projects for the nonprofit consumer advocacy group Consumers Union. “You can strike a balance with benefit design and education, not with simply denying coverage.”

The devil will be in the details, say observers such as Love and Imholz who are seeking to understand the immediate and long-term ramifications for hospitals and patients.

One key challenge will be more clearly defining "appropriate" emergency care, a concern raised by some Dallas Morning News readers on social media.

"So now you have to be your own doctor and determine if it's really a heart attack or indigestion before going to the hospital," one Facebook post read. It's "the ultimate Monday morning quarterback, but with millions of money at stake," wrote another.

Those are among the concerns that emergency providers will face.

Emergency rooms that accept federal money must, by law, evaluate everyone who walks in the door. If that starts to change, it could have legal implications, said Christian K. Puff, a Dallas-based health care lawyer with Hall Render, a national firm that represents medical providers.

There is a big risk, Puff said, in sending someone home with “sorry, you’re probably fine ... and then the member dies on the way home.”

There’s also worry that the effort could become a slippery slope.

“It may be HMOs today and PPOs tomorrow,” said Love, who would like to pull together insurers and medical providers for a discussion on emergency care issues.

Last year, the Indianapolis-based health insurance giant Anthem Blue Cross Blue Shield introduced a procedure change that sparked outrage, partly because it included a list of medical conditions that would not be covered.

Hospitals in states affected by the policy have already taken their arguments to court.

In a lawsuit filed in Atlanta's Fulton County earlier this year, a group of hospitals said Anthem never sought approval for the policy despite existing network-provider contracts.

The lawsuit accused the insurer of being motivated solely by a desire to reduce costs, regardless of potential consequences on access to care. A similar case filed in Virginia called the policy unilateral and aggressive.

It's too early to tell if Texas emergency providers will do the same. But it wouldn't be out of the question, given laws that require them to provide care and the fact that determining a medical emergency is not always straightforward, Puff said.

“That’s where the conflict is," she said. "In the gray area, in that ‘you should have known’ zone ... and in whether it’s fair to put that onus on the people and the providers.”

Medical providers that Puff's law firm represents have been closely following how the change plays out in other states.

"Like most people do when there's something unkown," she said, "they're preparing for the worst."