Databases

International Tax Treaties
RIA - Westlaw: RIA-TAXT (current) - treaties between the U.S. and other countries, technical explanations, Senate Committee reports, Secretary of State reports and other government documents.
International Tax Treaty Editorial Explanations
RIA - Westlaw: RIA-TAXTEX (current) - annotated analyses of treaties between the U.S. and other countries with citations to cases and rulings.
Tax Treaties and Explanations
RIA - Westlaw: RIA-TREATIES (current) - treaties between the U.S. and others with legislative histories and editorial explanations (combination of RIA International Tax Treaties and RIA International Tax Treaty Editorial Explanations)
Tax Treaties Case Law
Tax Analysts - Lexis: WWCASE (1890-current) - access worldwide tax court opinions
Tax Treaties U.S. Legislative History
Tax Analysts - Lexis: WWLEG (1932-current)
Uncle Fed
Open access website contains bilateral treaties between the U.S. and foreign jurisdictions (in pdf).
Worldwide Tax Treaties - Integrated Treaties Database
Tax Analysts - Lexis: WWPROC file (1950-current) - more than 150 tax treaties as amended by protocols, exchanges of notes, etc. (treaties in file and current form)..
Worldwide Tax Treaties Combined Files
Tax Analysts - Lexis: TAWTT (1828-current) - worldwide tax treaties and U.S. legislative histories; many English translations.
Worldwide Tax Treaties in Force
Tax Analysts - Lexis: WWFRCE (1910-current) - treaties that are currently in force organized by country and subject matter (i..e. coffee, sugar, etc).