Here is a comparison of the policy positions of Ron Paul and Bob Barr, courtesy of Third Party Watch.
Non-interventionism
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 respecting the sovereignty of other nations is necessary, not from only a moral standpoint, but to regain the respect of the world as a principled and peaceful nation.” – source
Iraq
Ron Paul: “The sooner we withdraw the better. The invasion and continued US occupation has strengthened both Iran and Al-Qaeda in the region. Continuing down the road of a failed policy will only cost more money we do not have and more lives that should not be sacrificed. Interventionism has produced one disaster after another. It is time we return to a non-interventionist foreign policy that emphasizes peaceful trade and travel and no entangling alliances. We can begin by withdrawing from Iraq immediately.” – source
Bob Barr: “I believe the occupation of Iraq—where we have a presence in a foreign country that effectively manages that country and provides the fundamental basis on which that country and government exists and operates—is not something that is sound policy and is not consistent with the historical norms of a national defense policy. So I think that we need to—and I would as president—begin immediately and significantly drawing down our military and economic presence in Iraq for two reasons: One, because it is not in our interest to nation-build or to occupy foreign lands and, secondly, if we would ever wish to have the Iraqi government take responsibility for its own affairs, we necessarily have to remove the security blanket that right now makes it very easy for them not to do so. In other words, they are never going to assume responsibility for their own affairs as long as we are there propping them up.” – source
Taxes and spending
Ron Paul: “A pure consumption tax like the Fair Tax would be better than the current system only if we truly did away with the income tax by repealing the 16th amendment. Otherwise, we could end up with both the income tax and a national sales tax. A consumption tax also provides more transparency and less complexity. But the real issue is total spending by government, not tax reform.” – source
Bob Barr: “Cutting spending would allow America to implement real tax reform. Our goal should be to reduce both the tax burden on Americans and the intrusion in their lives resulting from IRS enforcement of the income tax. One of the best approaches would be to adopt some form of a consumption tax, like a national sales tax, replacing the Internal Revenue Service and all federal income taxes as well as payroll taxes.
“It is not enough to eliminate the income tax. We also must repeal the 16th amendment, which authorizes Congress to levy an income tax. Without doing so, there would be an ever-present danger that a future Congress would attempt to bring back the income tax on top of the Fair Tax or any other alternative to the income tax. ” – source
Federal Reserve
Ron Paul: “The greatest threat facing America today is not terrorism, or foreign economic competition, or illegal immigration. The greatest threat facing America today is the disastrous fiscal policies of our own government, marked by shameless deficit spending and Federal Reserve currency devaluation. It is this one-two punch—Congress spending more than it can tax or borrow, and the Fed printing money to make up the difference—that threatens to impoverish us by further destroying the value of our dollars.” – source
Bob Barr: “If I could wave a magic wand and the Federal Reserve Bank would disappear tomorrow, I would do so. It’s a group of unelected governors that are not answerable to or accountable to the people of this country and yet they wield considerable influence over the economy by basically setting rates at which banks and other financial institutions can loan money. And they have built up, you know, huge reserves themselves that they can then dole out as they’re doing – as they did recently with Bear Stearns to prop up as failing, what they see as failing investment houses, for example.” – source
Individual rights
Ron Paul: “States, not the federal government, were charged with protecting individuals against criminal force and fraud. For the first time, a government was created solely to protect the rights, liberties, and property of its citizens. Any government coercion beyond that necessary to secure those rights was forbidden, both through the Bill of Rights and the doctrine of strictly enumerated powers.” – source
Bob Barr: “The United States was created for the purpose of securing the liberties of its people. The colonists fled oppressive old world governments. The nation’s founders drafted the Constitution to sharply limit the federal government’s powers. The horrors perpetrated by the many collectivist tyrannies of the 20th Century demonstrate that the danger of government, any government, violating individual liberty is greater today than when America was founded.” – source
Patriot Act
Ron Paul: “The Patriot Act waters down the Fourth amendment by expanding the federal government’s ability to use wiretaps without judicial oversight. The requirement of a search warrant and probable cause strikes a balance between effective law enforcement and civil liberties. Any attempt to dilute the warrant requirement threatens innocent citizens with a loss of their liberty. This is particularly true of provisions that allow for issuance of nationwide search warrants that are not specific to any given location, nor subject to any local judicial oversight.
“The Act makes it far easier for the government to monitor your internet usage by adopting a lower standard than probable cause for intercepting e-mails and internet communications. I wonder how my congressional colleagues would feel if all of their e-mail headings and the names of the web sites they visited were available to law enforcement upon a showing of mere ‘relevance.’” – source
Bob Barr: “The Fourth Amendment to the Constitution stands for the fundamental principle that the government cannot gather evidence against a person unless it has some tangible reason to believe that the person has violated the law (and that could include associating with terrorists). This reflects the principle that we are each, as citizens in a free society, clothed with a ‘sphere of privacy’ that the government cannot ‘pierce’ without a reason. If we were to take the position, reflected in provisions in the USA PATRIOT Act, that the government can invade our privacy and gather evidence that can be used against us based on no suspicion whatsoever that we’ve done anything wrong, but simply because the government wants to gather evidence as part of some generalized, ‘anti-terrorism’ or ‘foreign intelligence’ investigation, then we will have rendered that Fourth Amendment principle essentially meaningless. That is why this debate is so important.
“The notion that the government can gather evidence based on reasonable suspicion that a person has violated the law, also applies to a suspicion that the person is suspected of operating as an ‘agent of a foreign power’ (including a terrorist organization). This is appropriate; but in such a case also, the government should be held to the standard that it must first have some individualized suspicion that a person is an agent of a foreign power, and not that the government is on a fishing expedition.” – source
Real ID
Ron Paul: “We must stop the move toward a national ID card system. All states are preparing to issue new driver’s licenses embedded with “standard identifier” data – a national ID. A national ID with new tracking technologies means we’re heading into an Orwellian world of no privacy. I voted against the Real ID Act in March of 2005.” – source
Bob Barr: “Big Government advocates are personified by the current Bush administration, favoring central control of virtually every facet of activity in our society, from education to transportation and from the plumbing in our bathrooms to the bulbs in our lamps. While the Real ID debate shares some elements with its sister debate concerning voter ID, mixing the two as if two sides of the same coin dilutes the host of fundamental constitutional concerns and responsibilities affected by the Real ID Act program now being forced down the throats of the states.” – source
War on Drugs
Ron Paul: “I would [decriminalize drugs/medical marijuana], at the federal level. I don’t have control over the states. And that’s why the Constitution’s there.” – source
Bob Barr: “Today, I can reflect on my efforts and see no progress in stopping the widespread use of drugs. I’ll even argue that America’s drug problem is larger today than it was when Richard Nixon first coined the phrase, ‘War on Drugs,’ in 1972.
“America’s drug problem is only compounded by the vast amounts of money directed at this ongoing battle. In 2005, more than $12 billion dollars was spent on federal drug enforcement efforts while another $30 billion was spent to incarcerate non-violent drug offenders.
“The result of spending all of those taxpayer’s dollars? We now have a huge incarceration tab for non-violent drug offenders and, at most, a 30% interception rate of hard drugs. We are also now plagued with the meth labs that are popping up like poisonous mushrooms across the country.
“While it is clear the War on Drugs has been a failure, it is not enough to simply acknowledge that reality.” – source
More Ron Paul and Bob Barr goodness here. Many thanks to the dedicated Ron Paul/Bob Barr supporters who helped compile this list.