Courts view data structures, the mechanism by which computers store data in meaningful relationships, differently than do computer scientists. While computer scientists recognize that data structures have aspects that are both physical (how they are stored in memory) and logical (the relationships among the stored information), the Federal Circuit, in its attempts to set clear standards of the scope of patentability of data structures, has not fully appreciated their dualistic nature. This i-brief explains what data structures are, explores how courts have wrestled with setting a limiting principle to determine their patentability, and discusses the resultant impact on claim drafting