Mr Wasant filed a defamation lawsuit against Prompong, a former Pheu Thai Party list MP, and Kiat-udom, a former Pheu Thai MP for Udon Thani, after they publicly accused him of lacking in judicial ethics and impartiality on June 8, 2010.
The Criminal Court found the pair guilty of defamation and sentenced each to one year in prison and a fine of 50,000 baht. The custodial sentences were initially suspended for two years.
Mr Wasant took the case to the Appeals Court.
The Appeals Court today decided to lift the suspension on the sentences, ruling that the two defendants had intentionally insulted the judge and discredited the judiciary, despite being highly educated and holding political positions.