in someone else's shoes
Imagining oneself in the situation or circumstances of another person so as to understand or empathize with their perspective, opinion, or point of view. The expression is a set phrase, as the other person is not specified. If you haven't spent time in someone else's shoes, how can you judge them?
in someone else's shoes
and in someone else's placeFig. seeing or experiencing something from someone else's point of view. (See also in a bind and the examples.) You might feel different if you were in her shoes. Pretend you're in Tom's place, and then try to figure out why he acts the way he does.