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