which foot the shoe is on

Whose opinion, perspective, or interest is being considered or described. Usually used after "depends on." The legitimacy of these claims depends entirely on which foot the shoe is on. I know you think it doesn't matter which foot the shoe is on, but everything about this case changes if we look at it from a different point of view. The laws are impartial, and they should be applied the same to everyone, irrespective of which foot the shoe is on.