Patent system system integration has altered the balance between the interests of patent holders and society. Two turning points in this process are examined: the 1883 Paris Convention, and the1978 launch of the Patent Cooperation Treaty and the European Patent Convention. The article shows how these treaties evolved and how further integration occurred after their implementation, following unforeseen/unintended paths stemming partly from technological change. Overall, global patent system integration has increased the territorial reach of patents, curtailed national restrictions on their use, enhanced rights of patent applicants/holders, and broadened patentability definitions. Corporations, the dominant patent holders, are the principal beneficiaries of these changes. Patents have become powerful, sometimes hegemonic tools for corporations to control technology, people, and markets on a global scale. A case study shows how Monsanto used its European patents on GM soybeans to make Argentina change its patent laws, to the perceived detriment of Argentine farmers.