WASHINGTON - Unlike the Supreme Court's decision two years ago that gutted the law's mandatory Medicaid expansion, severely limiting the law's reach, the effect of the Monday ruling is more peripheral. The contraception provision was not part of the main law but rather was laid out in regulatory language issued by the Obama administration. Millions of women who receive birth control at no cost through their company health plans are likely to keep it.
Still, women who work for closely held, for-profit companies whose owners have religious objections to contraceptives may feel an impact.
The ruling is likely to inflame the debate about executive power that has arisen during President Barack Obama's second term. Congressional Republicans, who have threatened to file suit against Obama for his use of executive actions, were among the first to repudiate the president and the health law over Monday's ruling.
"Obamacare is the single worst piece of legislation to pass in the last 50 years, and I was glad to see the Supreme Court agree that this particular Obamacare mandate violates the (law)," Senate Minority Leader Mitch McConnell, R-Kentucky, said in a statement.
Some supporters lamented the ruling but insisted that the law remains strong and that Monday's decision will have a minimal impact on its core goal: reducing the number of the nation's uninsured.
They noted that the law itself only required company insurance plans to cover "preventive" services. The Department of Health and Human Services then used guidelines established by the Institute of Medicine to label birth control pills, intrauterine devices and sterilization methods such as tubal ligation services that are integral to women's preventive health.
Arts and crafts chain Hobby Lobby and cabinet-maker Conestoga Wood Specialties had objected specifically to methods that had the potential to harm a fertilized egg, such as IUDs, which work primarily by preventing fertilization but may also stop a fertilized egg from implanting in the uterus.
"Politically, of course, the case may be trumpeted as a major defeat for the ACA, but that is simply not true," said Timothy Jost, a health law professor at Washington and Lee University and a supporter of the law. "This case is not about the ACA. It is about religion, about employer and employee's rights, about corporate law, and I suppose about public health law, but it is not an existential challenge to the ACA."
It is the latest turn in the tortured path taken by the Affordable Care Act, which was enacted in 2010 after a pitched political battle and has encountered obstacle after obstacle since.
The Supreme Court upheld the constitutionality of the law in June 2012, at the same time that it made the expansion of Medicaid - the state-federal program for the poor - voluntary. Since then, 24 states, including Idaho, have opted not to enlarge the program. The collapse of the Medicaid expansion is viewed as one of the most significant failings of the law.
A challenge striking more directly at the heart of the law still looms: a wave of suits from citizens and employers who argue that the government is wrongly handing out tax credits in half of the states. If successful, this argument would cut at the heart of the law by making health insurance unaffordable for many people.
The contraception mandate became a much-lauded provision for the law's supporters, who pointed to it as evidence that the Affordable Care Act was particularly good for women. They hailed the law as an antidote for years of inequality, with women routinely paying more than men for their health care and insurance.
On Friday, the Obama administration touted new figures showing that the number of women who filed prescriptions for oral contraceptives with no copay increased from 1.2 million in 2012 to an estimated 31 million in 2013, which officials attributed in part to the Affordable Care Act.
"This is a hard-fought victory to get birth control coverage in the Affordable Care Act," Cecile Richards, president of Planned Parenthood, told reporters in a Monday teleconference. "Women are already benefiting. We are seeing a great uptake in the benefit. It's just that there are politicians and now judges who are trying to drag us back to the 1950s."
But for critics of the law, the mandate became the most high-profile exhibit for what they viewed as a pattern of government overreach during Obama's time in office.
In a decision that was widely criticized even by the law's supporters, the mandate initially applied not only to private companies but also religiously affiliated nonprofits that employ large numbers of workers from various backgrounds, such as Catholic hospitals.
Facing blowback, the administration made a change that allowed employees to bypass their employers and get contraception benefits through a third party. But it did not satisfy many employers. A second wave of legal challenges to the contraception mandate, from those nonprofits, is also making its way through the courts.
"This train-wreck law still does far more harm to American families than good, but it's encouraging to know that there are limits to the government's power to coerce," Rep. Phil Gingrey, R-Georgia, and Rep. Phil Roe, R-Tennessee, said in a joint statement from the House GOP doctor's caucus Monday.