Not every failed investment or unsuccessful business venture constitutes criminal fraud under Thai law. In public fraud and pyramid scheme cases, Thai courts carefully examine whether a legitimate business existed, the defendant’s intent, the evidence presented, and the circumstances surrounding the investment scheme. This article explains seven important legal defence strategies, including proving the business was genuine, demonstrating that the defendant was also misled, challenging allegations of public fraud, raising limitation period arguments, disputing the number of criminal counts, and presenting mitigating circumstances. Whether you are a business owner, investor, or defendant facing allegations of investment fraud, understanding these legal principles is essential when preparing an effective defence under Thai criminal law.