Legal Commentary

You have already checked your bags and gone through security in an airport in Europe such as Budapest's Ferihegy Airport.  You have 7,000 or so Hungarian forints ($35) just burning a hole in your pocket, so you decide to invest in a bottle of Zwack Sándor Nemes Pálinka (barack flavor - and that's not a tribute to our President - it's Hungarian for apricot, pronounced "bar-RATZK"), which you have sampled, and find to be a delightful way to anticipate your gulyas or your csirke paprikas. 

Being a thinking type, you say to yourself, "ah, but this is more than three ounces of liquid."  If I don't have a problem until I clear customs in Detroit, I can put it in my suitcase for the last leg to Traverse City."  The only issue will be if there is any problem in Amsterdam.  You say to the clerk in the duty-free store, "Will I have any problem with this in Amsterdam?"  To which the response is, of course, "no."

Learn from my experience.  There is a problem in Amsterdam.  If you are getting on an international flight from Schiphol Airport's international side, you will have to do a carry-on security check at the gate, and which point the security people will tell you that you cannot carry on your pálinka unless you bought it in the duty-free shop at Schiphol Airport, and that they confiscate dozens of bottles of booze and wine daily from travelers changing planes in Amsterdam, having bought the stuff in Prague, Budapest, Warsaw, or whereever (which they probably resell in the Schiphol duty free shop!). 

This, by the way, is what the behaviorial psychologists and economists call the "endowment effect."  Once something is ours, it takes on a value far beyond its cash value, merely because it is ours.  Experiments have shown that if you give a group of people equally worthless kewpie dolls, and then ask them to trade them, generally they won't, at least straight up, because each person's kewpie doll takes on a value to its new owner that is something more than worthless.  Suffice it to say that I did manage to repack my backpack and check it at the gate, and complete my plan in Detroit, but I was the last person to get seated on the plane as I negotiated to save the pálinka, and in good old-fashioned irrational actor fashion, for just a moment contemplated blowing hundreds of dollars missing my flight just to make a point about what a stupid rule it was.