I. Quill and the Nexus Requirement ... A. Bellas Hess in Perspective ... B. The Pre-Quill Climate ...C. The Quill Decision

II. Allied Signal and the Unitary Business Concept ... A. Apportionment and the Unitary Business Principle ... B. The Recent Precedents ... C. The Allied-Signal Court's Analysis of the Precedents and Determination of the Governing Principles ... D. Application of the Governing Principles ... E. The Dissent

III. Should the Nexus Requirement Apply Separately to Each Taxed Activity? ... A. The Due Process Clause Nexus Requirement ... B. The Commerce Clause Nexus Requirement ... C. The Relationship of the Due Process and Commerce Clauses

IV. Conclusion