The Appeal Court upheld the acquittal of Bio Clinic owner, Kaweewat Hengsawat, for allegedly performing unregis-tered new medical procedures in 2004.
Dr Kaweewat, formerly known as Paisarn Hengsawat, apparently turned various types of silicone, including bars, tubes and grains into tiny particles and mixed them with medicine which he injected into his patients during plastic surgery.
The prosecution said that the doctor did not obtain permission to perform such procedures from the Food and Drug Administration.
In December 2010, the lower court acquitted the doctor because of insufficient evidence.
The Appeal Court yesterday said that Dr Kaweewat had obtained a medical doctor's licence, adding there is still no firm conclusion as to whether silicone is classified as a drug under the 1967 Drug Act.
Accordingly, he did not intend to break any laws, the court said.
Dr Kaweepat said that since he is a doctor, he has the right to proceed with his medical practice.
The Criminal Court in 2008 also acquitted Dr Kaweewat in a case of fraud and recklessly causing severe injury to the late Raweewan Setarat, stemming from a plastic surgery procedure.
The surgery on Raweewan's face took place between April 2003 and February 2005.
Raweewan had filed charges against Dr Kaweewat over the cosmetic surgery which she said had permanently disfigured her face.
She was shot at her home in Bang Kapi and pronounced dead at the hospital in September 2007.
Crime Suppression Division officers later arrested two men _ Jaturong Benkul and Prakob Srinak _ for Raweewan's murder. The pair allegedly confessed to the murder during questioning. They later denied the charge in court.
The court of first instance in January 2010 cleared Mr Jaturong and Mr Prakob of premeditated murder, citing insufficient evidence.
