Defamation in Thailand may be in form of slander or libel. Incidents of defamation may occur in a business, political, or commercial context.

In Thailand, unlike many Western jurisdictions, defamation may be both a criminal offense and/or a civil offense. Defamation is a criminal offense in accordance with sections 326 -333 of the Thai Criminal Code. This means that under Thai law, a person convicted of defamation charges may be subject to imprisonment.

There are two kinds of defamation:

1) Simple defamation  — Whoever imputes anything, to the other person before a third person, in a manner likely to impair the reputation of such other person or to expose such other person to be hated or scorned.

2) Libel  — document publication, drawing, painting, cinematography, film, picture or letters made visible by any means, or any other recording instruments, recording picture or letters, or by broadcasting or spreading picture, or by propagation by any other means.

The burden of proof lies on the defendant to prove that his statements are true. The defense that the defendant did not know his statements to be false is not acceptable in Thailand. 

If found guilty of an offense, a sentence of up to two years imprisonment. 

Defamation can also be a civil offense under section 423 of the Thai Civil and Commercial Code. If found guilty, then the offender maybe ordered to pay a fine.