If I already know someone whose English reading and Thai writing skills are excellent, can I use that person to translate a Statutory Declaration and other legal documents?

Only if they are certified to do this. If this is for back home you need to go to your embassy for certification. Translation Thai to english can be done by individual that is recognized by the MFA..

It's for MFA to get married (English to Thai).

 

I actually used this person (who is not recognized by the MFA) years ago to translate my passport ID page in order to get a tabien baan (yellow book) successfully. I was wondering whether documents for marriage would be similar.

I think the safe route is to get it done by an accredited agency. I suspect the MFA will want to see an accreditation stamp on it when you submit it to them for "legalisation".

The translator must be accredited by the MFA. If you're going to the MFA in BKK, use the translation service on the second floor. I was there on Friday, they charge 400b per page for the express service. It took 40 minutes for the translation.

I've just come across a post that states the wife did the translation herself:

 

 2. Translation of 'freedom to marry' document - 0 (wife did it herself)

 

It's in the thread How To Arrange A Fast And Simple Marriage @ Amphur ?

 

I don't know if this has changed but years ago you could have anyone do the translation. In fact, I did my own translation of my daughters birth certificate Thai to English with my name signed as translator. Sent the translation and original copy to (I think it was) Dept of Consular Affairs on Chaeng Wattana road and the translation was certified and stamped. 

Used at the Australian and American Embassies with no problem. 

 

hyperdimension, on 07 Aug 2014 - 17:52, said:

I've just come across a post that states the wife did the translation herself:

 

Quote

 2. Translation of 'freedom to marry' document - 0 (wife did it herself)

 

It's in the thread How To Arrange A Fast And Simple Marriage @ Amphur ?

 

 

I'm also aware of similar cases where passports and affidavits were translated by Thai family members or friends with good English skills and accepted at the Amphur.

 

I suppose you'll never know if you don't try.