Document validation

Hi guys, i’m working on an HTTP library specifically designed to be used with JSON API and i’m trying to figure out the expected behavior in case of invalid json api request.
Can i return a 400 Bad Request or there is a better solution?

Did you read ?

Also check out content negotiation and the errors sections at the end of various sections. You’ll get a 4XX error, but the code might tell you quite a bit about what you did wrong.

** A 5XX is also possible, but less of a concern because it wouldn’t be your fault if it went wrong.