Chapter 6 explores the doctrines of indirect (secondary) patent infringement in the United States, Europe, and Japan, focusing primarily on novel statutory interpretation issues brought about by 3D printing technology. Indirect infringement generally requires knowledge of the patent or some sort of intent to infringe. Because 3D printing technology will empower many legally unsophisticated actors to assist – even if unwittingly – others to infringe, virtually every jurisdiction will need to clarify how to measure knowledge or intent when numerous individuals or small businesses are involved. In Europe, courts will also need to decide the fundamental issue of whether the knowledge requirement implies a culpable mental state. Additional statutory interpretation issues include what constitutes a “component” under U.S. law and what constitutes “means, relating to an essential element of the invention” under many countries’ statutes. In Japan, courts or lawmakers will need to clarify whether a “product” includes 3D printable files. The chapter concludes by recommending that courts and lawmakers resolve interpretive issues in a manner that captures at least the most egregious actors, namely, those who repeatedly and knowingly facilitate infringement by distributing DMFs.