The United States Supreme Court has upheld a key provision of the Affordable Care Act, also known as Obamacare, in a 6-3 decision. The ruling backs government subsidies that help more than 6 million Americans purchase health care on state-regulated Internet marketplaces.

Conservatives have challenged President Barack Obama's signature domestic program twice now and have lost both times. Back in 2012, the court ruled in favor of the individual mandate, which requires most Americans to buy health insurance or face a tax penalty.

The ACA has been controversial in the US. Supporters claim that the law provides Americans with greater access to better quality health insurance at an affordable price. Opponents criticize the ACA as an unnecessary intrusion in Americans' health care decisions that will drive up prices.

Since the implementation of the ACA began in 2014, the uninsured rate in the US has dropped from 17 to about 12 percent of the population.

Edmund Haislmaier, a health policy expert at the conservative Heritage Foundation, tells DW why he opposes the ACA, and the implications of the Supreme Court's ruling for those who oppose the law.

So what was stake in this challenge to ACA?

It came down to whether the administration's reading of the law was correct or not. So it upheld the way the administration interpreted the law.

As far as the health care issue is concerned, it would have affected a portion of the legislation in some states. It hinged on whether or not the administration was correct that the subsidy system in the law could be applied to states that had not set up health insurance exchanges, but the federal government was doing it for them. Essentially, the court said yes they can.

What does this mean politically and in terms of the health law going forward? It means that things will continue as they had in the past in terms of the health law, but that also means that there's a lot of other problems that the health law will encounter going forward.

Why are conservatives in the US opposed to the Affordable Care Act?

Stepping back even further, what is worth noting is that since before the enactment of this legislation five years ago and from that time through today, there has consistently been about half the country opposed to this legislation.

The question is why? At a very fundamental level, the reason is – as most people here and abroad are aware of – we in the United States have the most expensive health care system in the world. But we are not satisfied with it.

This law says we're going to address one thing that we don't like: Not everybody has health insurance - though those people are getting medical care, it's just that they don't have health insurance - and we're going to do it with a whole bunch of new spending.

I don't think the public ever bought the idea that the way to fix the world's most expensive health care system was to spend more money to cover the people who might not have health insurance. Even though we were already spending a lot of money on people who don't have health insurance to make sure they got medical care.

The other difficulty is that there are a lot of people who were perfectly happy with their arrangements before the law was enacted, who now see that their arrangements have been disrupted or that they are not only paying more for subsidizing other people, they're paying more for their own coverage.

That has formed the nucleus of opposition that Republicans have relied on.

What's the conservative alternative to the ACA?

The basic health care reform would be to change the way the system works.

Particularly to deregulate the central planning and micromanagement, to bring about things that would reduce the cost of care, that would encourage hospitals, physicians and insurers to compete on offering better results at lower prices, not compete on just charging more and doing more.

That would bring down the cost of the system thereby making sure that everybody gets coverage or everybody gets care in the system.

There's broad agreement across ideological lines in this country that Americans are not satisfied with what they're getting and what they're spending. We feel like we're paying too much for health care and not getting enough.

The disagreement between the left and the right is do you cover everybody, and then try to bring the cost down through increased central planning and regulation. That's what the Democrats and this legislation do.

Now that the Supreme Court has twice ruled in favor of the ACA, will the opposition accept the law as a fact of life or is the goal still to throw the whole thing out?

Keep in mind that prior to this legislation being enacted about 80 percent of the public was reasonably satisfied with their coverage and arrangements other than the fact that they thought it cost too much.

That 80 percent has found their coverage and arrangements many times disrupted and the cost actually going up, not down. That opposition to that frustration does not go away.

That means there will continue to be pressure to redo this law going forward. It will almost certainly not be in one big piece of legislation; it will almost certainly be incrementally, in pieces over a period of years.

So basically the battle is not over?

It's not even close to being over.

Edmund Haislmeier is a Senior Research Fellow on Health Policy Studies at the Washington-based Heritage Foundation