Not sure how "secret" it really is. The power of the regulatory agencies to make and enforce regulations with the power of law has been blasted for a long time. Scalia called out such bodies for being a "junior varsity Congress" way back in 1989.
I've always thought that regulations should not have the force of law unless and until they are expressly approved by Congress. The regulatory agencies can write whatever they wish, then just send it up to Congress for a vote at the end of the year.