Attorneys arguing before the Supreme Court refer to past decisions to help make their case.
Here's a look at five Supreme Court decisions that attorneys may cite in arguments today in the case of Conestoga Wood Specialties v. Sebelius.
Sherbert v. Verner (1963)
The Supreme Court ruled 7-2 that a member of the Seventh-day Adventist Church was entitled to unemployment compensation after being fired for refusing to work Saturdays, her faith's day of rest.
Adeil Sherbert, a South Carolina mill worker for more than 30 years, was fired when Saturday work became mandatory. Other mills would not hire her.
Justice William J. Brennan Jr., writing for the majority, said Sherbert should not be forced to abandon a precept of her religion to be eligible for a government benefit.
"Governmental imposition of such a choice," Brennan wrote, "puts the same kind of burden upon the free exercise of religion as would a fine imposed against appellant for her Saturday worship."
Brennan created the four-prong Sherbert Test for determining if the government was violating an individual's religious liberty.
The court must first weigh the person's religious sincerity and, second, decide if the government had imposed a substantial burden on the individual's religious freedom.
If the first two conditions are met, then the government must justify the burden by proving it has a "compelling state interest" and has pursued that interest in the least restrictive, or burdensome, way.
Wisconsin v. Yoder (1972)
The Supreme Court ruled 6-1 that the government cannot compel the Amish to educate their children past eighth-grade.
Jonas Yoder and two other families brought suit after pulling their children from high school in New Glarus, Wis.
Writing for the majority, Chief Justice Warren E. Burger said the state's interest in education "is not totally free from a balancing process when it impinges on fundamental rights."
He added that "however strong the state's interest in universal compulsory education, it is by no means absolute ...."
Burger said forcing high school attendance upon the Amish "is not only severe, but inescapable" as they are compelled "under threat of criminal sanction to perform acts undeniably at odds with fundamental tenets of their religious beliefs."
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Key court filings
United States v. Lee (1982)
The Supreme Court ruled unanimously that Amish businesses, like all businesses, must pay their workers' Social Security taxes.
Edwin D. Lee, an Amish farmer and carpenter in Lawrence County, objected to Social Security on religious grounds. His business owed the government $27,000 in unpaid Social Security taxes.
Noting that "not all burdens on religion are unconstitutional," Chief Justice Burger wrote that the state may limit religious liberty "to accomplish an overriding governmental interest."
"The tax system could not function if denominations were allowed to challenge the tax system because tax payments were spent in a manner that violates their religious belief," Burger wrote. ''To maintain an organized society that guarantees religious freedom to a great variety of faiths requires that some religious practices yield to the common good.''
He also noted that an exception for an Amish employer imposes "the employer's religious faith on the employees."
Self-employed Amish, however, are exempt from Social Security taxes.
Cutter v. Wilkinson (2005)
The Supreme Court ruled unanimously that federally funded prisons cannot keep inmates from practicing non-mainstream religions unless the prohibition furthers a compelling government interest.
The suit was brought by five prisoners in Ohio, including a Wiccan, a Satanist and a member of a white supremacist church.
They said prison officials denied them religious literature, group worship, ceremonial items and access to chaplains trained in their faiths.
Writing for the court, Justice Ruth Bader Ginsburg said the government failed to prove that the inmates' religious requests were overly burdensome.
"Should inmate requests for religious accommodations become excessive, impose unjustified burdens on other institutionalized persons, or jeopardize the effective functioning of an institution," Ginsburg wrote, "the facility would be free to resist the imposition."
Gonzales v. O Centro (2006)
The Supreme Court ruled unanimously that the government failed to prove a compelling government interest in seizing an hallucinogenic tea used by 130 New Mexican members of a Brazilian church.
The government argued for uniform enforcement of the Controlled Substances Act.
Writing for the court, Chief Justice John Roberts said, "The government's argument echoes the classic rejoinder of bureaucrats throughout history: "If I make an exception for you, I'll have to make one for everybody, so no exceptions."
Under the Religious Freedom Restoration Act of 1993, Roberts said, the court must grant exceptions in the absence of compelling government interest.