Treaties relevant to conflict of laws research in the United States may be found indexed in Treaties in Force* under the heading "Judicial Procedure," under the subheadings "Interamerican Agreements" or "Hague Conventions"; under the heading "Law, Private International"; by looking under the specific area of law, e.g., "Investment disputes;" or, in the case of bilateral treaties between the U.S. and an individual country, by looking under the name of that country.
For resources on researching treaties electronically and in print at the UW Law Library, see International Law: A Legal Research Guide to Public International Law