The unraveling of the Affordable Care Act presents a historic opportunity for change. Its proponents call it "settled law," but as Prohibition taught us, not even a constitutional amendment is settled law—if it is dysfunctional enough, and if Americans can see a clear alternative.

This fall's website fiasco and policy cancellations are only the beginning. Next spring the individual mandate is likely to unravel when we see how sick the people are who signed up on exchanges, and if our government really is going to...