Because of the fundamental differences between utility and design patents, including their purposes of protection, subject matter, and development processes, it is difficult to apply identical legal principles to both. Nevertheless, as demonstrated by the LKQ decision, U.S. courts have continued to seek greater alignment between the legal doctrines governing utility and design patents. As long as these efforts persist, the application of U.S. design patent law is likely to face ongoing challenges. The LKQ decision held that the Graham doctrine, which governs the assessment of non-obviousness in utility patents, should also apply to design patents. However, because the Graham factors were developed for utility patents, it is difficult to apply them directly to design patents. First, regarding the scope of prior art, the materials that an ordinary designer may encounter during the design process are virtually unlimited. If the scope of prior art considered in the non-obviousness analysis is defined too broadly, adequate protection for designs may be undermined. Second, in design, the overall visual impression is more important than differences in individual features. However, differences in overall visual appearance are inherently difficult to articulate through logical verbal analysis. Third, when assessing the non-obviousness of design patents, identifying a rationale or motivation to combine or modify prior designs remains particularly challenging. Considerable attention has been focused on how the USPTO and the CAFC will apply the Graham factors to design patents.