A design patent gives legal protection to the design of a product, in contrast with a "utility patent," which protects a useful innovation.
The value of design patents was shown in a spectacular manner by a billion-dollar verdict in favor of Apple Computer against its rival Samsung, based on three design patents owned by Apple (as well as three utility patents). Steve Jobs, contrary to conventional wisdom, was a big believer in obtaining and trying to enforce design patents. This verdict has not yet been tested on appeal.
Although the ability to apply for design patents has existed since the 1800s, this type of patent was disfavored in the 1900s in favor of other forms of intellectual property, such as trade dress. But in 2008 a decision by the U.S. Court of Appeals for the Federal Circuit, which set the precedent for patent law nationwide, increased the strength of design patents by weakening the testmaking the test whether an average person would mistake a rival product for a product that has a patented design. If that easy test is satisfied, and the design patent is valid and its holder may try to enforce it.