So what does the historic Supreme Court ruling Thursday mean for Georgia?

Importantly, it sets up some big decisions for Georgia lawmakers and the governor.

The justices, by a 5-4 decision, upheld the Affordable Care Act’s requirement that individuals obtain health insurance or face a penalty. That portion of the ruling got the lion’s share of immediate attention from the national news media.

But surprisingly, and very significantly, the court also made the law’s Medicaid expansion optional for states.

More than 600,000 uninsured Georgians were expected to gain coverage through that expansion of the Medicaid program, which covers people with low incomes and the disabled.

“This is the most important part of this decision,’’ said Bill Custer, a health insurance expert at Georgia State University. What the state decides to do will greatly affect Georgia’s insurance market, he said.

The court’s ruling also preserves the requirement for health insurance exchanges in the individual states, and Georgia will have to decide whether it will create its own or let the federal government do it. An insurance exchange is envisioned as a sort of Travelocity or virtual marketplace, where people will be able to shop for coverage based on price and quality.

Gov. Nathan Deal, an opponent of the law, said in a statement Thursday that ‘‘the highest court in the country let the American people down.’’

“While we recognize this is a huge setback for fiscal sanity and personal liberty, we are not giving up,’’ Deal said. “Georgians and the American people deserve high-quality, sustainable health care. Congress must now work steadfastly on repealing this law and replacing it with reforms that help taxpayers instead of hurt them.”

Right now, though, the Affordable Care Act will stand as a law, and that has implications for every American. The ruling preserves consumer insurance protections, such as the ban on insurers rejecting people who have pre-existing health conditions, or charging them a discriminatory premium.

More than 120,000 young adults in Georgia can stay on their parents’ health plans until they turn 26, a very popular provision of the law.

Georgia health care experts, meanwhile, were scrambling Thursday to figure out the ramifications of the court’s ruling on the Medicaid expansion. Deal’s initial statement did not make a reference to that part of the ruling.

The Medicaid decision ‘‘came out of left field,’’ Custer said.

It would mean that the state could forgo widening the eligibility limits that would lead to many more uninsured, poor adults to get coverage.

The federal government would pay 100 percent of the costs for the first three years of the expansion. Medicaid is jointly financed by the state and federal governments, with the latter picking up roughly two-thirds of the cost in Georgia.

But the state officials calculate that Georgia would still be on the hook for hundreds of millions of dollars over time if the Medicaid expansion went forward.

“It’s absolutely critical that Georgia expands our Medicaid program,’’ said Cindy Zeldin of the consumer group Georgians for a Healthy Future. Most of Georgia’s uninsured fall into the income category that would be newly eligible for Medicaid, she said.

If the state rejects the move, Zeldin said, ‘‘it won’t make as big a dent in the uninsured.’’

Custer said that those people may have to enter the exchange instead. That could drive up premiums for people in that marketplace, he said, if those poor Georgians had more health problems.

People buying insurance in an exchange would be eligible for a subsidy that could bring down the cost of insurance. The lowest-income residents could get nearly all of their premiums covered by that subsidy.

If the state decides to approve the expansion, it could get $9 in federal dollars for every $1 dollar of state money, he added.

Georgia leaders decided to wait till the court ruled before moving forward on building an exchange, which is required under the ACA.

“Even if we pass legislation next session, we’ll have only six months to get it up and running, ‘‘said Phaedra Corso, department head of health promotion and behavior at the University of Georgia’s College of Public Health. “If we’re unable to do so, then the federal government will have to come in to set up and manage the exchange, so that’s a really big deal.’’

Here’s how the ruling affects different groups:

Consumers

Most people without health insurance – in Georgia, they comprise 20 percent of the population – will be required to obtain coverage or face a penalty.

But people whose incomes are in the low or middle ranges will have access to subsidies and to a health insurance exchange, which is expected to lead to more stable prices for coverage. An exchange will bring down prices for many individuals and small businesses.

Adults and children who have pre-existing health conditions cannot be denied health coverage or charged a discriminatory premium due to a pre-existing condition, such as asthma, diabetes or cancer. It will make health insurance more affordable for them.

Currently, many with chronic conditions such as diabetes and asthma either aren’t offered insurance, or it soars in price to premiums that rival a mortgage payment.

More than 120,000 young adults in Georgia can stay on their parents’ health plans until they turn 26.

Rebates for sharp insurance increases will continue to flow to consumers. Georgians are expected to receive close to $20 million in rebates this year.

There will be full coverage for preventive benefits such as mammograms. “This will have a very positive impact on the health of the state and on reducing long-term costs,’’ said Russ Toal, a Georgia Southern University health policy expert.

Medicare

The 1 million Georgians who are Medicare beneficiaries will continue to receive preventive care with no deductibles or co-pays, and will still receive discounts under the prescription drug benefit.

U.S. Health and Human Services officials say the Affordable Care Act has led to $102 million in savings to Georgia Medicare recipients.

Medicaid

This is the big variable. Medicaid is already undergoing a restructuring by the state, and it’s unclear how the court decision will affect that process.

If Georgia decides to do the expansion under the Affordable Care Act, it would add more than 600,000 residents to the Medicaid rolls.

Hospitals and physicians

The Affordable Care Act has ignited payment reforms, where insurers and government programs have agreed to pay more to hospitals and doctors based on the quality of services they deliver.

The decision will likely continue the trend toward groupings of hospitals and doctors into accountable care organizations. It will also lead to further marketplace provider consolidation, and the creation of ‘‘patient-centered medical homes.’’

Medical providers will have to gear up, too, to make themselves attractive and available to insurers so they are included in the insurance exchanges.

Former U.S. Surgeon General David Satcher noted that the ACA promotes primary care and prevention, and changes the incentives for providers to do more procedures. The law, he said, “begins to reward quality of care rather than quantity of care.’’

Health insurance companies

Insurers still face much uncertainty. But there is clarity on the fact that they won’t be able to discriminate against people with pre-existing conditions.

Georgia insurance companies will be waiting to see how the state sets up its insurance exchange, or whether it allows the federal government to do it.

Employers

The decision won’t likely have much of an impact on large employers, though they are required to provide preventive benefits to workers. But for smaller firms, many will have to decide whether to cover their workers or face a penalty for not doing so.

Some small businesses may decide to drop coverage and let their employees buy insurance through the exchange, Custer said.

GHN will continue to update the story throughout the day.