But no politician wants his hand seen behind Davis' release and hence this mess. Only courts can release him now. Then pakistani politicians can show people that a genie took away Davis back to US.
AFAIK Davis seems to have immunity under international law. Ardeshir Cowasjee also agrees with such assessment. Immunity to diplomats is complete. If diplomats mess up, the host can by law only deport him and warn the sending country. And the situation would be like sending country is supposed to apologize and ensure nothing gets repeated. But here this situation can happen only in Pakistan. I mean now Pak is feeling the pressure from US