Wanchai’s practice focuses mainly on administrative and constitutional law, and regulatory law.

He has extensive expertise in administrative and constitutional law, frequently involved in sophisticated and innovative cases. He not only represents private plaintiffs in challenging the state, but also defends administrative agencies in the administrative courts and the Constitutional Court.

He has strong expertise in providing complex legal analysis on administrative procedure law, administrative court law, constitutional law, factory law, telecommunications law, energy law, procurement law, consumer protection law, and other regulatory laws. He teaches administrative and constitutional law at universities.

He is currently an adviser to the executive board of the Master’s Degree Project for Financial Executives (Special Class), Business School, Kasetsart University. He has been appointed, on attachment, as an expert member of the National Legislative Assembly.

He was a member of the Committee on Economics and Foreign Affairs, of the Lawyers Council of Thailand (2010–2013), and a member of the Committee on Law Drafting and Revision, of the Ministry of Justice (2009). He was a member of the sub-committee of the Extraordinary Committee on Intention Records, Archive and Minutes Scrutiny, of the Constitutional Drafting Assembly (2007), and a member of the National Human Rights Commission sub-committee on the Scrutiny of Violations of Economic, Social and Culture Rights (2010–2015).

Wanchai obtained his LLB from Thammasat University and is admitted to the Thai Bar. He received an LLM from Southern Methodist University, an LLM from the University of Pennsylvania, the Certificate of Achievement on the Training Programme for Administrative Case Officials for the General Public from Chulalongkorn University and the Office of the Administrative Courts, the Certificate on Administrative Justice for Executives, from the Administrative Justice College, of the Office of the Administrative Courts, the Certificate on Justice Administration for Executives from the Office of Justice Affairs, Ministry of Justice.