According Imam Khomeini, In the early days of Islam, the ideal Islamic government ruled twice: first at the time of the Holy Prophet Muhammad and secondly when Imam Ali ibn Abi Talib (peace be upon them) governed in Kufah.
They were the only two examples that the immaterial values dominated. In other words, they were governments of justice in which the rulers had never violated the law.
It happened in the government of the early Islam. During those two periods, a government of law was in control and perhaps we will never find another government of law with such qualities all over the world. In such a government, head was equal to the simplest citizen living there before the law.