When one tries to discuss the possibility that the government is over-reaching in their enforcement of the U.S. income tax, one will frequently run into people who will quote Romans 13, and say the 'higher powers' are ordained of God (because God is 'sovereign' after all, and nothing happens unless He allows it... or so they say). When I researched some of the language in those first few passages in the Strong's concordance, it seemed to me that the 'higher powers' referred to in those passages were those of a spiritual nature, and not mankind. Sort of like the commercials for Hebrew National hot dogs used to say something along the lines of 'we answer to a higher authority'.
So I just read a good article on another blog titled: Christian Indifference and Romans 13 that I wanted to mention here, it mentions many other biblical passages where obeying God meant going against the reigning authority. I did pick up some mis-spellings, but I still made it to the end of the article and liked the message. Check it out!