move the goalposts

To alter the rules or parameters of a situation in such a way as to suit one's needs or objectives, making it more difficult for someone else to succeed, keep pace, or achieve an opposing objective. I hate arguing with that type of person. As soon as you start wearing down their logic, they just move the goalposts on the whole thing! We're never going to get the book design finished in time if the publisher keeps moving the goalposts every couple of months like this! Claiming victory after cutting the tax by a small fraction when in fact you had said you'd abolish it altogether is really moving the goalposts, isn't it?

If someone moves the goalposts, they change the rules or aims in a situation or activity, in order to gain an advantage and to make things more difficult for the other people involved. He was always moving the goalposts so that we could never anticipate what he wanted. They seem to move the goalposts every time I meet the required conditions. Note: You can also say that someone shifts the goalposts. The administration is shifting the goalposts and changing its demands.

Change the rules in the middle of an enterprise, usually to make it more difficult for someone to succeed. The term originated in sports that use goalposts (soccer, rugby, football) in the second half of the 1900s. It soon was transferred to other enterprises. Jo Bannister had it in Liars All (2009): “. . . if they parted one day, she’d find someone to replace him . . . He didn’t blame her for that. It wasn’t Brodie who’d moved the goalposts.”