In the USA, a patent can be granted on a design, a design patent, and in regards to a patent that delivers "a new and pleasing appearance to an article of manufacture, whereby its sale is enhanced".1
In other jurisdictions, this novel intellectual property is known, and protected as an industrial design.
In Connecticut Paper, the Maryland District Court, under the presidency of Justice William Coleman, added that design patents should issue only upon ornamental or aesthetic features of a device, and "cannot dominate functional or utilitarian features. That is to say, when a design differs from the prior art merely through the addition of some feature placed there for purely functional purposes, such design is not patentable."
In Fuji Kogyo, Justice Boggs the United States Court of Appeals discussed the interplay of design patent, utility patent and trademark registration, including the different duration of the statutory protection for each, but adding these words which supplement those of Justice Coleman above:
"A design patent is directed to the appearance of an article of manufacture. However, if the particular design is essential to the use of the article, it can not be the subject of a design patent."
In Keystone Retaining Wall Systems v. Westrock, Justice Lourie of the United States Court of Appeals seized the opportunity to bless the law reports with a comprehensive statement of the law in regards to a design patent, as follows, taken from the opinion:
"A design patent protects the nonfunctional aspects of an ornamental design as shown in a patent. It is the appearance of a design as a whole which is controlling in determining questions of patentability and infringement.
"The first aspect of the test for design patent infringement is as follows: in the eye of an ordinary observer, giving such attention as a purchaser usually gives, two designs are substantially the same, if the resemblance is such as to deceive such an observer, inducing him to purchase one supposing it to be the other, the first one patented is infringed by the other. Thus, one cannot establish design patent infringement by showing similarity of only one part of a patented design if the designs as a whole are substantially dissimilar.
"The test for infringement begins with an examination of the overall similarity of the patented and accused designs. A patented design is defined by the drawings in the patent, not just by one feature of the claimed design. To find infringement, the accused design must be compared to the claimed design to determine whether the two designs are substantially the same."