United States v. Barlow is a Supreme Court case from 1978 that dealt with the issue of whether the federal government had the authority to regulate the safety of employees in the workplace. The case arose when the Occupational Safety and Health Administration (OSHA) issued a citation to Barlow's Moving and Storage Company for failing to provide a safe workplace. Barlow argued that OSHA had exceeded its authority and that the citation was invalid. The Supreme Court disagreed and held that OSHA had the authority to regulate workplace safety under the Occupational Safety and Health Act of 1970. The Court reasoned that Congress had the power to regulate workplace safety under the Commerce Clause of the Constitution, and that OSHA's regulations were a valid exercise of that power. The Court also held that OSHA's regulations were not overly burdensome and did not violate the Due Process Clause of the Fifth Amendment. The decision in United States v. Barlow established the federal government's authority to regulate workplace safety and has been cited in numerous subsequent cases.

In the dissenting opinion of United States v. Barlow, Justice William O. Douglas argued that Congress had not given the Secretary of Labor authority to issue an order requiring employers to keep records and make reports regarding employee wages and hours worked as required by Section 11(c) of the Fair Labor Standards Act (FLSA). He further argued that this was a violation of separation-of-powers principles because it allowed executive branch officials to exercise legislative power without congressional authorization or oversight. In addition, he noted that there were no standards in place for determining which employees should be subject to recordkeeping requirements under FLSA section 11(c), thus allowing arbitrary enforcement by executive branch officials. Finally, he concluded that if Congress wanted such regulations issued they could have done so directly through legislation rather than delegating their authority to another branch of government.