John Roberts' argument for saving Obamacare helping power legal challenge

Chief Justice John Roberts saved Obamacare in 2012 by calling it a tax. Now, his core argument is helping power a Republican-led legal challenge that threatens to sweep away the entire law.

The Affordable Care Act faces its third major legal test since President Barack Obama signed it in 2010, putting access to health insurance for millions of Americans and coverage for those with pre-existing conditions, such as cancer and diabetes, into question.

The appeals court case, heard in New Orleans on Tuesday, may also complicate the legacy of the...