After graduating from the prestigious Triam Udom Suksa School, Borwornsak studied law at Chulalongkorn University, obtaining a "gold-medal" first class honours degree in 1975 and was admitted to the Thai bar the following year.
During the 2005–06 Thai political crisis and after the dissolution of parliament, both Wissanu and Borwornsak distanced themselves from the Thaksin administration and resigned their respective government posts.
After the 2014 Thai coup d'état, Borwornsak was appointed member of the National Reform Council (NRC), serving as this body's deputy speaker.
[6] At the same time he was apprehensive of providing the court with too much power and successfully advised against mentioning it in article 7, a crucial provision for constitutional conflict situations.
[7] As a legal scholar, Borwornsak has published articles justifying the strong role of the monarchy in Thai politics, the severe punishment of Lèse majesté as well as the recurrent military coups toppling democratically elected governments in the country.
After his retirement from the Thaksin administration in 2006, he published a lengthy article about the "Ten Principles of a Righteous King" and their role in Thai constitutional tradition, lauding the monarch as the "Supreme Arbitrator and Conciliator of the Nation".
[9] Political scientist Eugénie Mérieau mentions Borwornsak, together with Wissanu Krea-ngam and Meechai Ruchuphan, as a leading example of academics who laid the legal foundations for authoritarian government in Thailand and an exponent of a "legal–military alliance for illiberal constitutionalism".