Lord knows, there is a libertarian case to be made against John McCain. Whether it's his hyper-interventionist foreign policy, disregard for constitutional liberties and individualism, or his up-front opposition to "the 'leave us alone' libertarian philosophy that dominated Republican debates in the 1990s," the 2008 Republican nominee has drawn fire from many free-marketeers through (as the Club for Growth has put it), his "philosophical ambivalence, if not hostility, about limited government and personal freedom."

But it would be inaccurate at best to claim that a McCain presidency offers zero potential upside for libertarians. After two years of studying the Arizona senator's habits (and coming to mostly critical conclusions), I can identify seven plausible reasons why a limited-government type might consider voting for the guy, even if I for one won't. Each reason, as you'll see, has as least one serious caveat.

The list:

1) He's a principled free trader, in a year that Democrats and Barack Obama are principled "fair" traders.

If you pore over John McCain's five books (each co-written by longtime aide and alter ego Mark Salter) you will see very little in the way of political philosophy and even less having to do with economic ideas. A notable and timely exception to that is free trade, where McCain for decades has been anti-protectionist and pro just about every trade agreement imaginable. Considering that Democrats have all but killed off their 1990s support for trade agreements, and are being rewarded by increased majorities in Congress, having a principled free-trader in the White House is one of the last best hopes that the single easiest anti-poverty program ever invented can continue and expand.

Caveat: He's also one of the biggest Washington enthusiasts for economic sanctions, which is the opposite of "free trade."

2) Divided government!

As George Will put it in his Washington Post column today, "Divided government compels compromises that curb each party's excesses, especially both parties' proclivities for excessive spending when unconstrained by an institution controlled by the other party. William Niskanen, chairman of the libertarian Cato Institute, notes that in the past 50 years, 'government spending has increased an average of only 1.73 percent annually during periods of divided government. This number more than triples, to 5.26 percent, for periods of unified government.'"

Caveat: McCain, who has a long history of cross-party dealmaking, would surely cooperate with the Democratic majority on any number of potentially questionable measures. Including but not remotely limited to overreactive Wall Street regulation, expensive and ineffective climate change schema, and overly bureaucratic immigration reform.

3) He would veto the crap out of spending bills, particularly those laden with pork.

From a purely theatrical point of view, the specter of McCain using the bully pulpit to shame porkariffic legislators ranks as one of the single greatest prospects of a GOP victory. He has a long and honorable record of at least rhetorically going after unnecessary earmarks, avoiding them in Arizona, and rooting out contractor abuse in defense spending. And he's arguably the Senate's biggest booster of a line item veto, which if nothing else indicates a willingness to use a pen that George W. Bush let gather cobwebs.

Caveat: Pork only amounts to so much of the federal budget. If McCain is successful in increasing U.S. troop levels by 150,000, and boosting defense spending to 4 percent of GDP, he could remove every last slice of pork in the federal budget and still come out deep in the red. And given the way that McCain is now demagoguing any vote against "emergency" supplemental war spending as a Vote Against Our Troops, you can bet that the ahistorical and wildly irresponsible funding of our trillion-dollar wars will continue unabated.

4) He's against torture, and wants to close down Guantanamo Bay.

McCain rightly believes that having Washington condone torture reduces America's moral high ground, puts U.S. troops at risk, and produces reams of useless and inaccurate information. He understands that such a policy greatly reduces the country's already-diminishing stock of "soft power," for no appreciable benefit.

Caveat: As a legislator, most of McCain's handful of "reforms" that became law ended up enabling as much as reforming the stated practice. So it was with torture, where McCain's reform legislation ended up jeopardizing habeas corpus, an eight-century-old legal concept he's gone on to officially condemn.

5) He believes in the urgency of reforming, not adding, entitlements.

Another of the few consistent economic principles John McCain has shown is the belief that Washington needs to reform its massive entitlement programs today, instead of leaving a demographic mess to future generations.

Caveat: George W. Bush believed the same thing, had a Republican Congress for more than half his presidency, and couldn't do squat about it.

6) He would conceivably push for a more humane and open immigration system.

One of the more attractive aspects to McCain as a human is his transparent allergy to racism and xenophobia, particularly when directed at Latinos.

Caveat: As mentioned, McCain's previous efforts on this front ended up producing pretty gruesome legislation. After almost losing the Republican primaries over the issue, it's doubtful that a McCain immigration package would improve in 2009.

7) He would, along with Sarah Palin, bring sexual tension back to the White House.

Awkward hugs, an aging flyboy, a jealous wife...bring the popcorn!

Caveat: If you appreciate politics solely as entertainment, there's no caveat at all.

But if you worry about the accumulation of power in Washington, D.C., you should probably think twice before assuming that John McCain would amass less of the stuff than his opponents. Even if there are silver linings in his presidential clouds.