Tomorrow, the Affordable Care Act goes back to the U.S. Supreme Court. The justices will hear arguments in a case called King v Burwell. It challenges Obamacare based on four words in the law’s hundreds of pages; four words addressing tax subsidies that help people pay for insurance. The plaintiffs claim that because of how the law is written, only people who buy coverage through state-run marketplaces should get subsidies. If they win, millions of people in the 34 states where the federal government runs the marketplaces could lose health care. California is not one of those states -- we have our own marketplace -- but today we take a step back and look at how this case came about in the first place. Who are the plaintiffs, and how did they get involved?