The role of U.S. congress on Impose of Sanctions against Iran

The United States political system depends on Separation of Powers that with dividing the power between branches and making check and balance system, each branch oversee to other branch. As a result, there is always struggle between president and Congress in foreign policy area because of this system. At the result, every branch is claiming that has priority in foreign policy under the constitution.
This intervention in each other roles has Appearance at U.S foreign policy against Iran so that every unit try to carry out himself politics against Iran. Thus, this research with using descriptive method and enacted laws against Iran in congress, also hearing about Iran, want to respond this main question that what role has congress in progress of U.S. policies toward Iran and how do that role. The hypothesis is that every time congress has entered to U.S. foreign policy decision-makings against Iran, with ratification the rules causes to U.S. behavior toward Iran become more attack and also with impose more severity policies. In respect with Iran, the Congress has tried to have upper hand over the president in determination of U.S foreign policy