Tell you what.
Since the hypothetical me lives in the enlightened State of California, our state funded university just last year (2011) discovered you coke snorting Utah Mormons are wrong - we just discovered that squirrels are solving complex differential equations! We, the State of California do hereby enact the "Cruelty Free Act of 2011" which states that, in lue of better words "all you coke snorting Mormons are idiots, and you can't use our seaports as a way to export your world famous '100% tested on apes, monkeys, dogs and cats shampoo'. In fact, our citizens are so abhorred by your abuse, we no longer allow our seaports to be connected to any business that tests anything on any animal".
Basically, since you Coke snorting utah residents rely on us smart Californians for lots of your software, fast food and other such nice things, you just got screwed out of spite. You Coke snorters tell us Californians to shove it and enact the "You Cannot Fly Over Our Airspace with any kind of Caffeine Product and You Cannot Convey Californian Software over our Fiber Optic Lines Act of 2011".
Now we are both pissed. We need to fly over your fifthly state to deliver our fine wine and we need your fiber to deliver our high-tech 3d Pornography . You need our seaport because most of your pepper spray imports, used to calibrate animal pain thresholds, come from China, who worked out a sweet deal on tarrif free trade with California. In fact, most other states besides California and Utah think china sucks and doesn't do any trade with them (walmart now sells high priced goods made in Deleware only).
What do you, President Paul, say to these two obviously pissed off states? Do you say "You guys are are both idiots" even if they go to a civil war over this? Do you say "Look, Utah, those eggheads in California are right - if squirrels can do differential equations, then squirrels are intelligent and you guys can no longer test on animals"? What if he says "Those socialist pigs in California are kooks, animals have no rights, test all you want!". Does California secede from the nation and if so what does that do to the Chinese trade relations with the remainder of the US? What if the EU agrees with California and stops doing any trade with the remiander of the USA?
This is obviously a silly example, but consider what happens when OPEC stops exporting oil to the entire country because all those bastards in California made Cow Porn legal and now youtube (a California based company) is flooded with Cow Porn? Since the price of oil will rise for all states until OPEC nations are satisfied that *the entire nation* stops their Cow Porn filth, what does President Ron Paul say? Dont forget, California doesn't care because they outlawed all petroleum use last year and aren't Dependant on OPEC in anyway.
Since you have to assume that other nations will treat us as a whole, how do you deal with interstate squabbles like this?