1. Introduction.- 2. Business Aspects of the Spare Parts Industry.- 3. Design Protection Relating to Component Parts of Complex Products (Spare Parts) in the EU and the U.S..- 4. Legislative Efforts Relating to Design Law in the Context of Spare Parts.- 5 Jurisprudence Relating to Design Law in the Context of Spare Parts.- 6. Considerations Towards a Compromise.- 7. Future Outlook: The Spare Parts Debate in the Era of 3D Printing.- 8. Conclusion....