Sunpasiri's practice focuses mainly on corporate and commercial issues, mergers and acquisitions, franchise, construction, real estate and property development areas.

He has very extensive experiences in mergers and acquisitions, from drafting and negotiating sales and purchase agreement, to conducting legal due diligence. He has represented both local and international clients in several cross-border mergers and acquisitions, in various industries, such as insurance, telecommunication, heavy industry, consumer products, hotel, food and drug, real estate and chemical products.

He has represented MP Particle Board Company Limited, a member of Mitr Phol Sugar Corp Ltd. and PSA (Port of Singapore) in share acquisitions, including Loxley Group in investment in Laos. He has also represented a Thai shareholder in the sale of shares in Karat Public Company Limited, advised Lehman Brothers (Thailand) Limited in acquisition of five-star hotels and resorts, offices buildings and service apartments in Thailand, and the Erawan Group Public Company Limited in acquiring a boutique hotel in Koh Samui. He has also advised individual investors including a Dutch investor in the building of a resort in Koh Tao.

Sunpasiri obtained his LL.B. from Chulalongkorn University; LL.M., Taxation from De Paul University and CIS/Eastern European Lawyers Program sponsored by the University of the West of England, Bristol.