The U.S. Supreme Court plans to hear oral arguments on a case that could affect the viability of the Patient Protection and Affordable Care Act (PPACA) public exchange system and PPACA insurance underwriting rules March 4.

The court also has agreed to let both parties in the case, David King et al. vs. Sylvia Burwell et al. (Case Number 14-114), submit briefs from interested parties.

The case hinges on whether the provisions in PPACA that created the public exchange system and the premium subsidy tax credits let the exchanges run by the U.S. Department of Health and Human Services (HHS) offer access to the tax credits. Some, especially PPACA critics, say the provisions let the state-based exchanges offer the tax credits but do not authorize the HHS-run exchanges to offer the tax credits.

A three judge panel at the 4th U.S. Circuit Court of Appeals ruled 3-0 in July on the King case that PPACA is so unclear that it does not indicate whether the HHS-run exchanges can offer the subsidy tax credits. Another provision gives the HHS secretary the right to resolve ambiguous exchange program provisions, and that should give HHS Secretary Sylvia Burwell the authority to decide whether the HHS exchanges can or cannot offer access to the tax credits, the court held.

A three-judge panel at the D.C. U.S. Circuit Court of Appeals ruled 2-1 on the same day in a similar case, Halbig et al. vs. Burwell et al., that the statutory text clearly makes the subsidies available only through state-based exchanges.

PPACA drafters prohibited issuers of major medical coverage from using personal health information when deciding whether to issue individual coverage, and from using personal health information other than age and tobacco use when pricing individual coverage.

To compensate for the cost of adding people with serious health problems to the ordinary health insurance risk pool, drafters required many individuals to buy coverage, and they created the subsidy in an effort to help low-income and moderate-income people pay for the required level of health coverage.

Some say eliminating the PPACA premium subsidy in states with HHS-run exchanges could destabilize the individual health insurance market, by making health insurance unaffordable for healthy, low-income and moderate-income people.