In Parshat Shoftim the Torah spoke about cities and states, in our parsha we hear about homes and the intimate side of our life.
In our homes there are no judges or police, but it is possible to be a king. We are obligated to be our own judges and policeman
כִּי תִֽהְיֶ֨ין לְאִ֜ישׁ שְׁתֵּ֣י נָשִׁ֗ים הָֽאַחַ֤ת אֲהוּבָה֙ וְהָֽאַחַ֣ת שְׂנוּאָ֔ה וְיָֽלְדוּ ל֣וֹ בָנִ֔ים הָֽאֲהוּבָ֖ה וְהַשְּׂנוּאָ֑ה וְהָיָ֛ה הַבֵּ֥ן הַבְּכֹ֖ר לַשְּׂנִיאָֽה.
If a man has two wives, one loved and one hated, with children from both, and the first born from the hated wife.
The Torah tells us about a man who made a legitimate choice (then) to marry two women, but because of human nature one becomes loved and one hated. His love of the loved one brings him to try and give a preferential inheritance to his non- first born son.