According to the reason and philosophy of powers separation, scientists and experts in public law mention it as a guaranty for security and prevention against despotism. Therefore the principle of the powers separation is one of the most vital discussions about natural rights of nations which are due to controlling political power and preventing power centralization. In Islamic republic of Iran the main patterns of political system is based on separation of powers' principles and aims to prevent power centralization and related corruption. In this essay for more acquaintance with powers separation in west and also present Islamic scientists ideas. On the other hand we will discuss the different types of separation of powers and founded systems.
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