John Boyd practiced administrative and treaty law in the Office of the Legal Adviser in the US Department of State from 1972 to 1980. He practiced administrative and multilateral finance law in the Office of the General Counsel of the Asian Development Bank (ADB) from 1980 to 1999. From 1994 until 2002, he advised the ADB Office of Environment and Social Development. From 1999 until 2002, he was a Senior Sector Specialist on Sustainable Development in the ADB Office of Environmental and Social Development and later Principal Sector Specialist in the ADB Regional and Sustainable Development Department. In 2000 and 2001, he was part of ADB delegations at UN Climate Change Convention meetings in Buenos Aires and Marrakech.
In a private capacity, John Boyd participated in Climate Change Convention meetings at The Hague in 2000, Bonn in 2001, and the Earth Summit in Johannesburg in 2002. From 2003 to 2006, he has a guest lecturer in a course on sustainable development taught in the Harvard University Extension School. Since 2007 he has been teaching at the San Beda University Graduate School of Law.