The Criminal Court on Friday acquitted seven people and six companies of charges relating to "zero-dollar" tours organised for Chinese visitors.
They were accused of operating tour guide services without charging fees, damaging tourism, taking advantage of tourists, operating unauthorised tour guide services and laundering money.
Those charged included Somkiat Khongcharoen, 58, managing director of Fuan Travel Co; Thawal Jaemchokechai, 60, an executive of Fuan Travel; and Winit Chantharamanee, 70, a manager of the same firm.
The others were from the same family: Nisa Rojrungrangsi, 62, managing director of Royal Gems International Co, Thai Herb Co, Bangkok Handicraft Centre Co and Royal Paradise Co; her husband Thongchai, 61; their son Wasurat, 27, managing director of OA Transport; and their daughter Saithip, 36, director of Baan Kanom Thongthip.
Also charged were six companies: OA Transport Co, Royal Gems International Co, Thai Herb Co, Bangkok Handicraft Centre Co, Royal Paradise Co and Baan Kanom Thongthip Co.
Prosecutors arraigned them in court on Oct 25 last year after authorities on Aug 27 raided companies allegedly involved in the country's biggest zero-dollar tour network.
They were accused of operating illegal, poor-quality package tours and related businesses catering mostly to Chinese visitors.
Zero-dollar tours are cheap package deals in which tourists are pressured to buy overpriced goods and services from selected outlets at their destination.
In its ruling, the Criminal Court said the defendants rented tour coaches and sold products to tourists, but did not operate tour guide services.
The court also ruled that "zero-dollar" tours were actually a marketing strategy in a fiercely competitive industry, with about 300 tour firms in the country, and the tourists had been charged in China.
Police investigators had never checked the shops and businesses of the defendants. Therefore, there was insufficient evidence to back the charges, the court said.
The Anti-Money Laundering Office earlier seized assets worth more than 10 billion baht from the defendants, pending legal prosecution.