This study examines the interaction between intellectual property rights and international investment law from the perspective of developing countries. The central concern is that intellectual property rights, when afforded protection as "foreign investment" under investment treaties, may serve as grounds for claims against host states through investor-state dispute settlement (ISDS) mechanisms. This situation is particularly consequential in domains such as public health, access to medicines, patent validity, trademark restrictions, and compulsory licensing, where it may exert pressure on the regulatory space of developing countries. Drawing upon Third World Approaches to International Law (TWAIL) and the concept of "intellectual property responsibility," this article argues that the protection of intellectual property should not be construed in a manner that undermines the balance between private rights and public interests inherent in the intellectual property system — particularly the balance reflected in the Agreement on Trade-Related Aspects of Intellectual Property Rights (TRIPS). Accordingly, the adoption of an intellectual property responsibility framework, coupled with a more restrictive definition of investment, the safeguarding of domestic adjudicatory decisions, and the explicit incorporation of intellectual property exceptions and flexibilities in investment treaties, can serve as instruments for preserving the regulatory sovereignty of the host state.