Last year my youngest sister-in-law, a Thai national, married an Englishman. Turns out the geezer is a bit of a perve, actually a closet sicko who only slowly came out of his weird idiosyncratic closet (not a gay closet), and she wants to get far away from him and I want to send him back to England. I am urging her to take the perve for all he is worth. My wife wants her to only take 1/2 the property. Should she hire a lawyer or just use the system to extract well deserved punishment? I'd be happy to front her the money for a good lawyer if such a thing exists in Chiang Mai.

Any thoughts?

Going the way your wife suggests is the best for many reasons. Hiring a lawyer and attempting to extract vengence only perverts the one seeking vengence as it warps one's life for a long time. The process is difficult and unrewarding.

If she can divorce by agrement, taking one-half at the amphur, do it.

Put her mistake behind her ASAP and go on with her life is the best thing to do.

If all assets are here a split would probably be best (but anything in wife name only is hers alone). You should probably arrange for her to have someone go with her if a visit to amphur is method used, even if not a lawyer someone with a degree will help get fair treatment/respect.

Remember to keep immigration advised as things develop.

Further to my PM. I fully agree with ProThaiExpat. Going for vengeance is a soul-destroying process and leaves one open to revenge attacks oneself. It is normally better to walk away with whatever one can salvage without too much pain. Wash hands and get on with life.