How to handle REST Exceptions?

We are in the middle of a ongoing discussion about how to handle REST exceptions.

Response Content type : JSON

Two solutions we have:

1. Throw all the unchecked exceptions as a JSON response.
2. Send Request Invalid Response code.

Arguments:

• When its a error, why return JSON? Just send a invalid response code.

Counter Argument:

• Response code are too technical to handle for normal developers.

Whats your say??