22 U.S.C. § 4068

Notwithstanding any other provision of this part, any benefit payable under this part to a surviving spouse, former spouse, or surviving former spouse that would otherwise terminate or be lost if the individual remarried before 60 years of age, shall not terminate or be lost if the remarriage occurred on or after November 8, 1984, and the individual was 55 years of age or over on the date of the remarriage.