The issue has been put before the high court before, but this time justices will decide if the Trump administration has given too much leeway for employers to claim exemption under the ACA. In two prior cases in 2014, the Supreme Court weighed whether the Obama administration was too limiting with exemptions.
Churches and houses of worship are exempt from the birth control mandate and some religious-affiliated entities have been given a chance to opt out. The Trump administration in 2017 attempted to expand exemptions to other nonprofits, small businesses and individuals with non-religious moral objections.
Federal courts have prevented Trump administration rules from taking effect after attorneys general in several states objected.
"This is a dispute that is fundamentally about the rights of religious people and it only makes sense to have the Little Sisters [of the Poor] in the case to express that position," said Mark Rienzi, president of the Becket Fund, which represents the religious order that filed original objections to the mandate.
Pennsylvania Attorney General Josh Shapiro has argued there are already options for certain employers to exclude contraception in benefit packages.
Wednesday is the third straight day the Supreme Court session will be streamed online via teleconference.
Cornell Law School professor Nelson Tebbe said more than 100,000 women in the United States could lose access to no-cost contraceptive coverage if the high court sides with the Trump administration.