Who pays when someone without insurance shows up in the ER?

From USA Today:

If an uninsured patient shows up in the emergency room, who pays? The hospital? Taxpayers? The patient? Other patients?

The question is important as Republicans debate health care legislation that could result in more than 20 million fewer Americans having health insurance in ten years. If that happens, some people will go without care. Others will show up at hospitals, but won’t be able to pay their bills.

The year the Affordable Care Act passed, hospitals provided about $40 billion in “uncompensated care” — that is, care they were not paid for. That was nearly 6% of their total 2010 expenses.

A 1985 federal law requires emergency departments to stabilize and treat anyone entering their doors, regardless of their ability to pay.