U.S. Supreme Court justices have heard arguments in a case that puts the federal Affordable Care Act's "contraception mandate" under the spotlight, as well as the rights of for-profit corporations. Two family-owned businesses say they'll have to violate their religious beliefs to comply with a federal requirement that employee health care plans cover certain kinds of birth control.

Conestoga Wood Specialties, a Mennonite-owned business based in Pennsylvania's Lancaster County, has joined with the Christian family-owned Hobby Lobby crafts stores and affiliated book stores. Owners of both companies say they should get a religious exemption from providing certain contraception in their employees' health care plans.

Lawyers argued in court Tuesday about whether for-profit corporations can claim religious exemptions to federal law. Justice Elena Kagan said, if the court rules for Conestoga Wood and Hobby Lobby, religious objectors will "come out of the woodwork" to challenge a number of federal laws.

But attorney Paul Clement, representing the plaintiffs, said the court can narrowly define who can claim a religious exemption – for example, not extending such a definition to include publicly traded corporations with shareholders.

Some liberal justices questioned how a for-profit corporation could be deemed to exercise religion, especially if owners are split on the subject. But Justice Antonin Scalia said it's simple – "whoever controls the corporation" decides if the corporation is religious.

The government's lawyer, Solicitor General Donald Verrilli, said providing women the full range of birth control should be considered of utmost importance, and if the two challengers win, their female employees will lose statutorily guaranteed rights.

Clement said the government can ensure access to such contraceptive methods without involving employers at all – for example, by setting up a program that bypasses employers completely. But Verrilli contends employers may object later if they are even minimally involved – for example, having to sign a form to let workers obtain certain birth control methods.

"I think we should have a good outcome, but I've been surprised before in this case," said Randy Wenger, a lawyer for Conestoga Wood. He said he's been with the case "since day one."

"If we just switched the scenarios around, sometimes that makes it easier for people to understand what's at stake with them," Wenger said. "Mennonites are conscientious objectors to military service ... imagine if Conestoga Wood were being forced during wartime to provide components for military service and the government were saying, 'You're a corporation ... your religious liberty's not implicated because we're only telling your business to do this."

"In a free country," Wenger continued, "shouldn't there be some escape valve where we're not forcing people to do things that violate their most basic convictions?"

A ruling is expected sometime this summer.