It is not permitted to the most equitable of men to be a judge in his own cause.

Fairness does not survive self-interest, no matter how fair the person is. When your own stake is in the question, the weighing goes wrong in ways you cannot feel from inside, because the thumb on the scale is invisible to the hand it belongs to. This is not about dishonesty. It is a structural limit, which is why every serious institution puts the decision somewhere other than with the interested party.

In any dispute where you stand to gain, get a judgement from someone who does not. Say the case against yourself out loud to them and see whether it holds up better than you expected.