This is called the frustration of purpose. It's a doctrine about how cases would be solved if unforeseen circumstances were to occur. A modern example would be if you took a mortgage but an earthquake completely destroyed your house. Due to the frustration of purpose, you could have your mortgage canceled because you don't have a house that the mortgage was for, so you wouldn't have to pay for it any more.
It was named after the ship, the Mayflower. Because it was them who the Mayflower Compact governed. The Mayflower Compact was the first agreement for self government in America. Hope this helps.
