Investment treaty policy increasingly interacts with business responsibilities. This scoping paper first surveys the converging approaches to responsible business conduct (RBC) and business and human rights (BHR) as reflected in the OECD Guidelines for Multinational Enterprises, the United Nations Guiding Principles on Business and Human Rights and core ILO standards. Legislative developments and court cases are examined. The paper focuses primarily on government action as part of a flexible “smart mix” to address RBC and maximise the positive contribution of business to sustainable development, but also examines some business and civil society action.Three aspects of trade and investment treaty interaction with business responsibilities are considered: treaty impact on policy space for governments including for the non-discriminatory regulation of business; treaty provisions that buttress domestic environmental, labour or other law; and provisions that speak directly to business by, for example, encouraging RBC or establishing conditions for access to investment treaty benefits.