The court's invalidation of the Medicaid expansion was less shocking but equally important. Conceptually, the ACA is a two-legged stool for expanding access: One leg—the individual mandate—expanded access for about 16 million middle-class individuals by mandating they purchase health insurance. The other leg—the Medicaid expansion—expanded access for another 16 million poor individuals by forcing states to extend Medicaid to them. Recognizing the states' sovereign right to opt out of an expensive Medicaid expansion effectively took a chainsaw to one of the ACA's two legs, leaving a politically wobbly and unstable structure.