After some brief remarks, President Johnson signed into law the Medicare Social Security Amendments. Johnson gave the first souvenir pen to Mrs. Truman and the next to President Truman and then the remainder of the pens to guests on the platform.on Archives.gov). This act was signed into law by President Lyndon Johnson on July 30, 1965, in Independence, MO. It established Medicare, a health insurance program for the elderly, and Medicaid, a health insurance program for the poor.