Wanchai’s practice focuses mainly on administrative, constitutional law and regulatory law. He is the head of the Administrative and Constitutional Law Practice Group.

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 is currently a legislative expert attached to a Senator, and also serves as an adviser to the executive board of the Master’s Degree Project for Financial Executives (Special Class), Business School, Kasetsart University.

He was a legislative expert attached to a member of National Legislative Assembly (2014-2019), 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).

He has been consistently acknowledged by Asialaw Profiles as a leading lawyer in Regulatory & Government in 2009, 2010, and 2012. In Dispute Resolution, Asialaw Profiles listed him as a leading lawyer in 2011-2014 and 2016-2022 consecutively.For Chambers & Partners Asia Pacific, he has been recognized in Dispute Resolution as a Band 2 leading Lawyer in 2015 and as a Band 3 leading Lawyer in 2018-2021. He was also ranked as a Band 2 leading Technology, Media, Telecoms Lawyer in 2017.The Legal 500 Asia Pacific listed him as a leading individual in Dispute Resolution in 2018 and 2019 and as a recommended lawyer in 2021. Wanchai has been named one of Thailand's top 100 lawyers – a definitive “A-List” of the country's legal profession by Asia Business Law Journal. Benchmark Litigation Asia-Pacific has ranked him as a Dispute Resolution Star in Government and Regulatory in 2019 and 2020.

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.

He received the Certificate of Achievement on the Training Program for Administrative Case Officials for General Public from Chulalongkorn University and Office of the Administrative Courts, the Certificate on Administrative Justice for Executives from the Administrative Justice College of Office of the Administrative Courts, the Certificate on Justice Administration for Executives from Office of Justice Affairs of Ministry of Justice, as well as the Certificate on Performance Support for National Legislative Assembly and National Reform Steering Assembly, and the Certificate on Experts and Specialists Attached to Members of National Assembly, both from King Prajadhipok’s Institute, National Assembly.