Private environmental governance continues to gain legal environmental academic attention. Newer bilateral and regional trade agreements have been encouraging the use of private environmental governance as a potential counterpart to traditional environmental regulation. The recently signed Trans-Pacific Partnership (TPP) is one such trade agreement. Its provisions, however, differ from earlier trade agreements in ways that may limit the flexibility of private governance mechanisms. This essay examines the private governance provisions of earlier free trade agreements involving the United States. It then provides a preliminary exploration of the voluntary mechanisms provision of the TPP, and observes the ways in which the voluntary mechanisms provisions of the TPP Agreement differ from earlier agreements to which the United States is a party. It concludes by highlighting potential academic areas of exploration related to these developments, and suggesting considerations that legal decision makers may want to keep in mind when approaching these provisions.