This Article applies the concept of "legal transplant" to the slavery regimes that sprang up in all regions of settlement during the first two centuries of English colonization of mainland America. Using a distinction between "extrastructure" and "intrastructure," we can divide the Anglo-American law of slavery into discourses of explanation/justification and technologies of implementation. The two components were produced from distinct sources. English law possessed few intellectual resources that could be mobilized to justify and explain slavery as an institution. Here we find the law of nature and nations uppermost. English law offered many resources, however, for the management, distribution and control of movements of people. Thus, the Anglo-American law of slavery combined two transplanted resources within itself. As colonial settlements turned into slave societies, local innovations increasingly supplemented original transplants, compensating for their deficiencies and limitations and becoming, in turn, a third species of transplant. Assembly laws moved from colony to colony, creating commonalities within regions of settlement, and also — more interestingly — among regions usually thought quite distinct. Together the three species of transplants created densely instrumental slave regimes that enumerated all the ways in which summary mutilations and executions defined the slave’s life on the edge of death.