“To engraft upon the Social Security system a concept of ‘accrued property rights’ would deprive it of the flexibility and boldness in adjustment to ever changing conditions which it demands,” Justice Harlan wrote for the Court.

“It is apparent that the non-contractual interest of an employee covered by the [Social Security] Act cannot be soundly analogized to that of the holder of an annuity, whose right to benefits is bottomed on his contractual premium payments.”

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