What is the ruling of Islamic law regarding demanding retribution (qisas) from a person who cut off the ear of the questioner's brother, taking into consideration verse 45 of Surat Al-Ma'idah, and what should be done if the tribal elders do not rule accordingly?

The implementation of hudud (punishments) is only valid when carried out by the ruler. Therefore, retribution (qisas) against the offender is not permissible except by those authorized to do so, such as tribal elders, either through reconciliation, qisas, or diya (blood money). Otherwise, the matter should be referred to the Sharia judiciary to rule according to Allah's law.