The Dragon Registration Act is a piece of legislation enacted by the Magus Senate of Dalaran. It applies specifically to the Senate and not to Dalaran or the Kirin Tor as a whole, thus making it not a part of the standard Laws of Dalaran.
The Act states that any person applying to become a member of the Senate must disclose if they are a Dragon. Because applications are reviewed only by members of the Senate's Inner Council, this information is not accessable to the public. If someone joins the Senate and does not disclose the fact they are a Dragon to the Council, it is grounds for immediate expulsion. There is a provision allowing for members who joined the Senate previous to the Act's passage to come to the Council at any time without reprecussion.
An accident in the records involving a bat and three fireball spells has led to the exact date of passage being lost, but the document is still in good enough shape that the Act is valid. It's notable for being one of the few Senate laws to bypass the Senate itself and go straight to the Inner Council for a vote, rather than being voted on by the Senate and ratified by the Council.