Using Michel Foucault's concept of modes of objectification, this paper argues that treaties, declarations, and agreements constitute international juridical forms that transform human beings into legal subjects. It retraces the objectification of “natives” in nineteenth-century colonial treaties that made human beings accessories to territories and transformed them into colonial subjects. This legal construct, the paper contends, was rendered unstable in the UN era when treaties re-objectified the “natives” into “peoples”, thereby allowing colonial subjects to re-subjectify themselves into actors and re-describe themselves with an adjective, a nationality. The paper then brings the history to the twenty-first century and posits that ASEAN is now objectifying new trans-national subjects that are ontologically connected to the regional economy. This history of legal subjectivity reveals not only the power of international juridical forms as a mode of objectification, but also the trajectory of subject formation in Southeast Asia under the ASEAN Charter.