Supreme Court takes up high-stakes battle over health law subsidies, bathed in politics

Insurance coverage for millions of people is riding on the latest politically charged Supreme Court clash over President Barack Obama's health care overhaul.

The case being argued Wednesday focuses on who's eligible for federal tax subsidies intended to make health coverage affordable. Three years after Chief Justice John Roberts saved Obama's health law in an epic, election-year fight over its constitutionality, the chief justice could again hold the pivotal vote.

The current challenge devised by die-hard opponents of the law, also known as Obamacare, relies on four words — established by the state — in the more than 900-page law to argue that the vast majority of people who now get help paying for their insurance premiums are ineligible for their federal tax credits.