Here is a comparison of the policy positions of Ron Paul and Bob Barr, courtesy of Third Party Watch.
Ron Paul: “Non-interventionism is not isolationism. Non-intervention simply means America does not interfere militarily, financially, or covertly in the internal affairs of other nations. It does not we that we isolate ourselves; on the contrary, our founders advocated open trade, travel, communication, and diplomacy with other nations.” – source
Bob Barr: “Our National Defense policy must renew a commitment to non-intervention. We are not the world’s police force and our long, yet recently tarnished, tradition of