We have a Thai friend who has left Thailand to be with her family abroad.  She had a bad experience with another Thai in a property transaction in Thailand.  She has posted online about the person and the transaction now the other party is threatening to go to police.  The posting was done in another country so can she be charged ?   Thanks in advance.

Unbelievably, here, even if it's true you can't say it. Defamation is not civil but criminal, here, and another demonstration that Thailand is still in the Middle Ages. Someone with specific knowledge should post soon but I would think the problem would only be 'a problem' if she planned to come back?  good luck anyway.