Strange analogy with a rugby game, which, as far as I know, are never reversed. However, political decisions frequently are. Obvious example, clause 28, passed in 1988, repealed in 2003, and in fact, in Scotland in 2000. It's a cornerstone of parliamentary politics that one parliament cannot bind the next. And as we are seeing recently, MPs frequently change their mind. Otherwise, we would be operating under Lord Palmerston's edicts.