I have never heard of a specif law that bans the taking of a lawn gnome on a vacation. Checking with the state department and costums before international travel could be important. Also check with your airline if you are flying and have fun.
I don't think I have ever heard of a law where you couldn't take your lawn gnome on vacation, but I would suggest you don't carry it on the plane with you because it might be considered a weapon and you will get some interesting looks.
