Hell, even when traveling domestically to other states you should ask that question and research where you're going.

The states concept is something that is mostly relevant to the US. The different in states in for example Germany is extremly limited.

I feel like this is really only relevant to gun laws/hunting. Not sure what other laws are as swiss cheese as they are.

There's also pot legalization differences between states, combined with Federal concerns.

Go to Colorado and buy some edibles, you're fine. Carry some over the border into Kansas, and not only are you breaking Kansas law, but if caught they may hand you over to the Feds and penalties may be severe. (Crossing a state border makes it a Federal issue.)

Correct me if I'm wrong but it's a federal issue and can be enforced even if you don't cross state lines. There's a drug case where Scalia seemingly ignored his previous opinion about what can be regulated as "interstate commerce" that I remember.

True, I'm sure there's something they can get you on without crossing state lines, but in a legal-pot state at least the local cops probably won't turn you in.

That something is possession.

Yeah kind forgot about that.

This is sounding more and more like you're advocating against traveling the world at all.

Not at all. Its advocating to think about your own actions. If you make a reasonable calculation to travel to Somalia, it might be a wonderful experience with limited risk,just think before you act.