Law 

Congress, and only Congress, enacts laws.

Federal executive departments and administrative agencies write regulations to implement the authority of laws.

Regulations (as well as Executive Orders and Proclamations) are ancillary or subordinate to laws but both laws and regulations are enforceable.

• U.S. Code
  The official compilation of codified laws by subject
  
  
• U.S. Statutes-at-Large
   The official chronologic compilation of all laws
  
  
• Federal Register
  Consists of two publications and should be used together to find the latest version of a regulation:
  • the annually revised Code of Federal Regulations (CFR)
  • the daily Federal Register (FR)

from Organizing Federal Laws and Regualtion USGS

Code of Federal Regulations
The Code of Federal Regulations (CFR) is a codification of the general and permanent rules published in the Federal Register by the Executive departments and agencies of the federal government.The CFR is divided into 50 titles which represent broad areas subject to Federal regulation. Each title is divided into chapters which usually bear the name of the issuing agency.

Available from the following providers:

• GPO Access - info
  Federal regulations: Federal Register, Code of Federal Regulations, U.S. Attorney General Opinions, and Federal Acquisition Regulations and Supplements
• LexisNexis® Academic  - info
  Federal regulations: Federal Register, Code of Federal Regulations, U.S. Attorney General Opinions, and Federal Acquisition Regulations and Supplements
• Westlaw's Campus Research ™ - info
  Federal regulations published in the Federal Register and the Code of Federal Regulations (CFR)

Federal Register

The Federal Register (FR) is the official daily publication for Rules, Proposed Rules, and Notices of Federal agencies and organizations, as well as Executive Orders and other Presidential Documents. Helpful Hints provide instructions for searching the database. Documents may be retrieved in ASCII "TEXT" format (full text, graphics omitted), Adobe Portable Document.

Available from the following providers:

• GPO Access - info
  Federal regulations: Federal Register, Code of Federal Regulations, U.S. Attorney General Opinions, and Federal Acquisition Regulations and Supplements
• LexisNexis® Academic  - info
  Federal regulations: Federal Register, Code of Federal Regulations, U.S. Attorney General Opinions, and Federal Acquisition Regulations and Supplements
• Westlaw's Campus Research ™ - info
  Federal regulations published in the Federal Register and the Code of Federal Regulations (CFR)