"Laws are written and passed by the Legislative Branch, signed and implemented by the Executive Branch, and can be challenged through the Judiciary Branch. The President, as head of the Executive Branch, holds the power to direct the activities of Federal Agencies as long as instructions do not come in conflict with decisions of other branches.
The many types of legal instruments in the US are a product of this three branch system. The types of legal and policy instruments discussed on this website generally come from the Legislative and Executive Branches of government.
The most common types of legal instruments discussed are laws and regulations. Laws are passed by both branches of Congress and signed by the President. Laws establish requirements or prohibitions. Regulations are published by executive branch agencies to clarify their interpretation of a law and how a law will be implemented. Regulations also state requirements or prohibitions.
Some agencies also publish guidance or other policy statements, which further clarify how an agency understands and implements existing laws and regulations. Guidance and other policy statements describe suggested or recommended actions. Guidance and policy statements do not provide mandatory requirements unless they are incorporated into a regulation or mandated under terms and conditions of an agreement, such as a funding agreement."