This time, the issue revolved around a 1994 federal law known as the Religious Freedom Restoration Act (RFRA), which Alito's opinion said prevents the government from "taking any action that substantially burdens the exercise of religion unless that action constitutes the least restrictive means of serving a compelling government interest."

Alito wrote that the court's conservative majority rejected the argument by the Department of Health and Human Services that "the owners of the companies forfeited all RFRA protection when they decided to organize their businesses as corporations rather than sole proprietorships or general partnerships."

"The plain terms of RFRA make it perfectly clear that Congress did not discriminate in this way against men and women who wish to run their businesses as for-profit corporations in the manner required by their religious beliefs," he wrote.

Complex mix

Monday's case presented a complex mix of legal, regulatory, and constitutional concerns-- over such hot-button issues as faith, abortion, corporate power, executive agency discretion, and congressional intent.

The political stakes were large, especially for the future effectiveness of the health law itself, which marked its fourth anniversary this spring.

The botched rollout of HealthCare.gov, the federal Obamacare website, was another political flashpoint along with other issues that many Republicans say proves the law is unworkable.

They have made Obamacare a key campaign issue in their fight to take control of the Senate while retaining their House majority.

"Today's decision is a victory for religious freedom and another defeat for an administration that has repeatedly crossed constitutional lines in pursuit of" big government, said House Speaker John Boehner, an Ohio Republican. "The President's health care law remains an unworkable mess and a drag on our economy."

Rep. Debbie Wasserman Schultz of Florida, who heads the Democratic National Committee, framed the ruling as a campaign issue for November.

"It is no surprise that Republicans have sided against women on this issue as they have consistently opposed a woman's right to make her own health care decisions," she said, calling the ruling a "dangerous precedent."

Barbara Green, a founder of Hobby Lobby, called the ruling "a victory, not just for our family business, but for all who seek to live out their faith."

However, Senate Majority Leader Harry Reid of Nevada said the decision "jeopardizes women's access to essential health care," adding that "your boss should never be able to make your health care decisions for you."

Contraception mandate

The section of law in dispute requires some for-profit employers to offer insurance benefits for birth control and other reproductive health services without a co-pay.

A number of companies equate some of the covered drugs, such as the so-called morning-after pill, as causing abortion.

The specific question presented was whether these companies can refuse, on the sincere claim it would violate their owners' long-established moral beliefs.

Supporters of the law fear the high court setback on the contraception mandate now will lead to other healthcare challenges on religion grounds, such as do-not-resuscitate orders and vaccine coverage.

More broadly, many worry giving corporations religious freedom rights could affect laws on employment, safety, and civil rights.

The abortion link