Some competitions may state in their terms and conditions that if you are a winner, or potential winner, you will be required to sign various documents prepared either by the organiser of the competition, or by its sponsors, or both. The rules often go on to say that should you fail to sign such documents you must forfeit your winning place in the competition, another entrant will be offered a winning place instead.
Normally, the documents you are required to sign in the circumstances described above are not displayed in full on the competition website. Therefore you can have no knowledge of what the terms and conditions in these documents will require of you. Yet, you are required on entering the competition, to agree to all the terms and conditions, even those not published.
This is a bizarre and and thoroughly bad business practice. No one of sound mind should ever be expected to sign an agreement the full terms and conditions of which are not available to read. You can be sure that in their business dealings the competition organiser would never sign an agreement without reading the full terms and conditions. Neither should you, do not enter such contests.
If you would like to know more about copyright and related rights please read our Guide to Rights and Licensing.