Other than the four main primary sources of law, there are a few other sources that have varying degrees of enforcement and power. Executive materials include executive orders, which are orders by the president or governor to an administrative agency, have the full binding force of law. A treaty is a formal written agreement between two or more sovereign nations, which is governed by international law. In the U.S., only the president or member of the executive branch are authorized to negotiate treaties. But all treaties negotiated by the president must be endorsed by the U.S. Senate before it is official. Treaties are also called international agreements, international conventions, and international protocols. Attorney General opinions are issued by both the U.S. and the Louisiana state attorney generals. Attorney General opinions are written interpretations of existing law. They cannot create new law. Though they are considered highly persuasive by courts, they are not authoritative. Municipal ordinances are passed by local municipalities such as cities or towns, and have the full force and effect of law.