clearances are hierarchical; each level grants the holder access to information in that level and the levels below it. The US president can declassify previously classified information, following a detailed process. Gaining access For people that require a security clearance to get access to classified information, an in-depth background investigation is conducted primarily by the Defense Counterintelligence and Security Agency, and the recipient signs a nondisclosure agreement. As of 2017, certain government officials (but not their staff) are granted access to classified information needed to do their jobs without a background check: members of the U.S. Senate and House of Representatives for committee work, federal judges and state supreme court judges for adjudicating cases, and state governors. Attorneys representing clients in cases with classified materials require a background check, but there is a reduced-scrutiny procedure for time-sensitive access. This ex officio access can be revoked. Pending a full security clearance an applicant may be granted a temporary security clearance of indefinite duration, which gives the applicant access to classified information while the original application is being vetted. Access to any particular piece of information requires "need-to-know." In some cases, this requirement is only nominal, as some classified information is widely published on secure networks. In other cases, there is a formal need-to-know determination. In addition to such a determination, Special Access Programs and Sensitive Compartmented Information may require additional investigation and adjudication of the prospective clearance holder. As of 2020, the cost of obtaining a Top Secret clearance is $5,596 while a Secret is $433. These costs are paid for by revolving government funds and not by contractor companies. Authority The authority for classifying information and granting security clearances to access that information is found in executive orders (EOs) and US Federal law. The United States' National Security Information (NSI) has been classified under Executive Order 13526, but since 10 January 2017 the rules were modified by James Clapper as Security Executive Agent Directive 4 in the closing days of the Obama administration. Information may be classified under this Order if a classification authority determines its unauthorized release could cause damage to the national defense or foreign relations of the United States. Information concerning nuclear weapons and fissile material may be classified under the Atomic Energy Act of 1954 (AEA). These clearances are only granted by the US Department of Energy. The clearance process for access to NSI or AEA