In Halbig v. Sebelius, four individual taxpayers and three employers are challenging a seemingly obscure IRS decree. The IRS claims the authority to issue hundreds of billions of dollars in subsidies to health‐​insurance companies, and to impose penalties on individual taxpayers and employers, in the 33 states that have refused to establish a health insurance “exchange” under the Patient Protection and Affordable Care Act (PPACA). The Halbig plaintiffs assert this decree would penalize them in violation of the clear, consistent, and unambiguous language of the PPACA, as well as congressional intent. The Congressional Research Service writes that Halbig “could be a major obstacle to the implementation of the Act.” Law professor Michael Greve writes, “all of ObamaCare hangs on the outcome.” The lead attorney in Halbig, Michael Carvin, and three other panelists will discuss the legality of the IRS’s decree and the implications for the PPACA.