at will - Legal Definition
Webster's New World Law Dictionary Copyright © 2010 by Wiley Publishing, Inc., Hoboken, New Jersey. Used by arrangement with John Wiley & Sons, Inc.
A status or relationship that can be terminated for any reason, or for no reason, at any time without prior notice.
at will - Phrases/Idioms
Freely, as one pleases, as in The grounds are open to the public and one can wander about at will, or With this thermostat you can adjust the room temperature at will. [1300s]