EDITORIAL: Congress' inaction killed ACA subsidies. Now, millions may lose health insurance.

Congress— notably, the Republicans who control both chambers— not only knew of this approaching threat but solely had the power to squelch it. Signed into law by President Barack Obama in 2010, the ACA is the most consequential health reform policy in the United States since the creation of Medicare and Medicaid in 1965. The ACA's safety net for more affordable…