Does a translator need to be certified?
The answer, as with most things in life, is it depends. The US has no official translator certification body. The closest we do have is the American Translators Association (ATA), which offers certification exams in certain language pairs (for example, German into English). The certification exam consists of translating a few passages, which are then graded by ATA graders. So, hiring a certified translator will ensure you have hired someone that can pass a tough exam in certain subjects – most likely not the same one as your document’s. It is not a subject matter exam because frankly, it would be impossible to test translators in every field, and no one is expected to be (or should try to be) a jack of all trades.
If you need a Chinese document translated into English, do not bother looking for a certified translator, because the ATA does not offer certification in this language pair. I decided that my time and money were better spent becoming a subject matter expert in medicine and a strong writer. After all, there are lots of certified translators out there, so this is not how to differentiate yourself from the pack. The real test is the quality of the work I deliver!