Debates over intellectual property rights often heat up around confrontations between those wanting more protection and those wanting less. But perhaps more attention should be paid to the detailed structure of legal rules governing these assets as they are actually used in real-world transactions.

One IP contract that has touched millions of consumers is Apple Inc.’s music license for iTunes, which purports to govern the use consumers can make of the music they download from Apple to their computers and iPods. That contract highlights some too-often-overlooked interactions among the laws governing copyright fair use, misuse and federal pre-emption of state law.