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).) Various other taxes are typically called "indirect taxes," because they tax an event, rather than somebody or property per se. (Steward Machine Co. v. Davis, 301 U.S. 548, 581-582 (1937).) What was a straightforward limitation on the power of the legislature based on the su...