The law behind Social Security is The Social Security Act, signed into law by President Franklin D. Roosevelt in 1935. Since that time, it has undergone numerous changes and additions. In 1954, President Eisenhower signed amendments to the Act that brought about disability benefits. Over the years, more amendments have been made, evolving the program to what it is today. In addition to Social Security Disability Insurance benefits, for which a person becomes eligible based on his/her past work, the Supplemental Security Insurance (SSI) program was enacted in 1974, providing disability benefits on a needs-basis. The Social Security Act defines disability as, the “inability to engage in any substantial gainful activity by reason of any medically determinable physical or mental impairment which can be expected to result in death or which has lasted or can be expected to last for a continuous period of not less than 12 months.” (The Social Security Act Â§ 223) Although that definition is short and succinct, it takes thousands of pages of laws, regulations, ruling, and policies to explain just what that really means and how it is to be applied. Social Security law is vast and complex. In fact, the section of the Code of Federal Regulations (CFR) associated with Social Security covers 1435 pages, most of which is dedicated to the two disability programs. Additionally, Social Security has a Program Operations Manual (POMS), which establishes the policies used on a daily basis by the Social Security field offices and a manual used by hearing offices. There are also rulings which provide an expansion of and supplement to the regulations. For this sheer volume of legal material, it is important to obtain an attorney who has a thorough knowledge and understanding of the law and the skills to apply it to specific cases.