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 Denver. v. C.I.R., 227 F.2d 16, 19-20 (3rd Cir. 1960).) All other taxes are commonly referred to as "indirect taxes," basically tax an event, rather than particular or property per se. (Steward Machine Co. v. Davis, 301 U.S. 548, 581-582 (1937).) What turned out to be a straightforward limitation on the power of the legisl...