Whether the federal payroll tax imposed on employers was a valid excise tax that satisfied the Constitution's uniformity requirement.
Holding
Yes. The tax was a valid duty, impost, or excise on the employment relationship, and it was geographically uniform.
Reasoning
Congress's taxing power extends to taxes on business activities, occupations, transactions, and relations such as employment. The Court rejected the argument that employment is an inherent right rather than a taxable privilege: lawful business activity is no less subject to taxation because it is pursued as of common right. Historical practice also included taxes on employers and servants, undermining the claim that excises are confined to commodities or luxuries.
The tax was not a capitation or another direct tax requiring apportionment. In any event, the Court explained that the constitutional categories of duties, imposts, and excises are comprehensive enough to encompass this levy on the employer-employee relationship.
The Constitution requires geographical uniformity for excises, not identical practical effects on every taxpayer. Because the same rule of liability applied throughout the United States, the statute met the uniformity requirement.