By: Mir M.Hosseini
The sixth Parthian king Mehrdad I ordered codification of a general constitution against which all citizens were to know their rights and responsibilities. Thereafter two parliaments were created that together formed the Iranian senate or Mehestan. Among duties of Mehestan were choosing the crown prince, declaring war or peace, dismissing the king in case of sanity or impotence, changing tax regulations, ordering mintage, etc. In many cases Mehestan authorized the kings as the heads of armies during wars.