Tehran: Public Diplomacy

As previously mentioned, the public opinion and political analysts' opinions would play an effective role on formation a nuclear agreement. Therefore, it is necessary for the Islamic Republic of Iran to first create a political unity in the country because as long as there is no political unity in the country, the discourse will not form; and second, political officials should use exclusive card of "good faith" to attract international public opinion and analysts' vote of confidence, the card that was recently burnt in Congress and the crisis of Yemen by Washington and gave away to Iran; and thirdly, Islam (in Muslim world arena) and international law are the only accepted discourse for Tehran. 
The nuclear agreement will form on the basis of the international law. After agreement realization, none of its parties have the right to review or violate it. The Article 27 of the 1969 Vienna Convention on the Law of Treatises stated that: 
"A party may not invoke the provisions of its internal law as justification for its failure to perform a treaty." 
And also the first section of the article 46 of the Convention: 
"A State may not invoke the fact that its consent to be bound by a treaty has been expressed in violation of a provision of its internal law regarding competence to conclude treaties as invalidating its consent..." 
P3+3 states have adopted the Convention (although the concept of the articles is part of customary international law); therefore, violation of any agreement is unauthorized and causes the international responsibility of states. It is obvious, particularly on the Iran nuclear negotiations that concerns over Congressional movement has no place in the reality; however, it reveals the legal knowledge. 
In all of the international agreements, it is agreed on the issue of "legal settlement of disputes" via inclusion some provisions and clauses in the main agreement or through contract an independent agreement. 
It seems that International Court of Justice would have more appropriate effectiveness and competency in dealing with all of the international agreements disputes. And it is not a popular idea to resume wholly or in part the Iran's nuclear program in the case of breach by the other party (i.e. P3+3).