by the Office of Legal Affairs, including signature, ratification and entry into force. In function and effectiveness, the UN has been compared to the United States federal government under the Articles of Confederation. Adding and amending treaty obligations Reservations Reservations are essentially caveats to a state's acceptance of a treaty. Reservations are unilateral statements purporting to exclude or to modify the legal obligation and its effects on the reserving state. These must be included at the time of signing or ratification, i.e., "a party cannot add a reservation after it has already joined a treaty". Article 19 of the Vienna Convention on the law of Treaties in 1969. Originally, international law was unaccepting of treaty reservations, rejecting them unless all parties to the treaty accepted the same reservations. However, in the interest of encouraging the largest number of states to join treaties, a more permissive rule regarding reservations has emerged. While some treaties still expressly forbid any reservations, they are now generally permitted to the extent that they are not inconsistent with the goals and purposes of the treaty. When a state limits its treaty obligations through reservations, other states party to that treaty have the option to accept those reservations, object to them, or object and oppose them. If the state accepts them (or fails to act at all), both the reserving state and the accepting state are relieved of the reserved legal obligation as concerns their legal obligations to each other (accepting the reservation does not change the accepting state's legal obligations as concerns other parties to the treaty). If the state opposes, the parts of the treaty affected by the reservation drop out completely and no longer create any legal obligations on the reserving and accepting state, again only as concerns each other. Finally, if the state objects and opposes, there are no legal obligations under that treaty between those two state parties whatsoever. The objecting and opposing state essentially refuses to acknowledge the reserving state is a party to the treaty at all. Amendments There are three ways an existing treaty can be amended. First, a formal amendment requires State parties to the treaty to go through the ratification process all over again. The re-negotiation of treaty provisions can be long and protracted, and often some parties to the original treaty will not become parties to the amended treaty. When determining the legal obligations of states,