In the high-stakes battle between Apple Inc. and Samsung Electronics Ltd. that took place in federal court in San Jose last summer, the money and the possible economic consequences garnered much of the attention. But the case highlighted a significant change during the last quarter-century in the world of intellectual property law: the steep rise in importance of the design patent.

Back in 1988, Apple sued Microsoft Corporation, alleging that the company had infringed its copyright on the “look and feel” of the Apple Macintosh’s graphical user interface. That suit, which Apple ultimately lost, was a copyright case in which Apple had to show that Microsoft had actually copied the design and appearance of Apple’s computer. In 1994 the U.S. Court of Appeals for the Ninth Circuit ruled that under copyright law, “Apple cannot get patent-like protection for the idea of a graphical user interface.”