Treaties are there to address double-taxation. That's their principal function. For me, the main reason that a treaty exists is that it establishes an international dispute-resolution mechanism to resolve cross-border disputes. Because we don't have a world tax court, we need to have some method of resolving cross-border disputes. Treaties create that mechanism; nobody has mentioned that yet today. That's the value of a treaty to a taxpayer.
On June 17th, 2013. See this statement in context.