The Achilles’ heel of democracy.
About four decades ago, most of the children S.S.I. covered had severe physical handicaps or mental retardation that made it difficult for parents to hold jobs — about 1 percent of all poor children. But now 55 percent of the disabilities it covers are fuzzier intellectual disabilities short of mental retardation, where the diagnosis is less clear-cut. More than 1.2 million children across America — a full 8 percent of all low-income children — are now enrolled in S.S.I. as disabled, at an annual cost of more than $9 billion.