When you know a double standard exists, at what point do you just let is slide?

Conversations have gone round and round and one side believes there is no double standard, or that the double standard issue lies with you. While you can admit that sometimes you may have a double standard in certain areas the other person refuses to admit or acknowledge the existence of a double standard on their part.

At some point, the double standard becomes so blatantly obvious that only a blind person could miss it, what do you do?

Sometimes I just don’t know what to do as the rules only seem to apply to me, but not to others.