The courts have generally held that direct taxes are restricted to taxes on people (variously called capitation, poll tax or head tax) and property. (Penn Mutual Indemnity Corp. v. C.I.R., 227 F.2d 16, 19-20 (3rd Cir. 1960).) All the other taxes are typically called "indirect taxes," as these tax an event, rather than human being or property as such. (Steward Machine Co. v. Davis, 301 U.S. 548, 581-582 (1937).) What was basically a straightforward limitation on the power of the legislature based...