From my sources in the State Dept!
Guidance on Non-Binding Documents
Governments frequently wish to record in writing the terms of an understanding or arrangement between them without, by so doing, creating obligations that would be binding under international law. The language, titles, and techniques used for this purpose vary considerably. While not binding under international law, a non-binding instrument may carry significant moral or political weight. Such instruments are often used in our international relations to establish political commitments.
Ambiguity as to whether or not a document is legally binding should be avoided. When negotiating a nonbinding instrument, both/all sides should confirm their understanding that the instrument does not give rise to binding obligations under international law. In all cases, the draft text should be reviewed by legal counsel familiar with the matters dealt with in the instrument. Also, the Office of Treaty Affairs encourages agencies and offices to share the texts of proposed non-binding documents with this office, which is responsible by law for determining whether a particular document is a binding “international agreement” for purposes of reporting to Congress.
Certain formal, stylistic, and linguistic features tend to be associated with agreements binding under international law, while other features tend to reflect an intent on the part of the participants to produce an arrangement of a purely political nature.
For example, we generally advise that an intention to conclude a binding international agreement may be indicated by employing terminology such as “shall”, “agree,” “undertake”, “rights”, “obligations”, and “enter into force.” When negotiators seek to conclude a non-binding instrument, we generally advise them, for example, to avoid terms such as “shall”, “agree”, “undertake”, or “party”; and to express that the instrument “come into operation” or “come into effect” for the “participants.” Also, we recommend where possible that the “participants” include a disclaimer in the text of the document expressly providing that it is not legally binding under international law.
It should be noted that U.S. practice on non-binding documents may differ significantly from that of other countries. For example, for the United States, the use of the verb “will” in the text does not necessarily mean that the commitment at issue is not legally binding under international law. Because the use of the term “will”may lead to confusion as to the intention of the participants, the Office of Treaty Affairs generally recommends that this term be avoided in non-binding documents. Also, the use of a title such as “Memorandum of Understanding” for a document does not automatically denote that the document is non-binding under international law. The United States has entered into MOU’s that we consider to be binding international agreements.
In sum, the Office of Treaty Affairs reviews the status of international instruments on a case-by-case basis, and a determination whether a document constitutes an international agreement or is a non-binding instrument is made on the basis of a number of criteria, including the identity and mutual intention of those entities involved, rather than simply the form or title of the document.