Apple Computer sued Microsoft and Hewlett-Packard for copyright infringement related to visual elements in the Apple Lisa and Macintosh operating systems that were similar to elements in Microsoft and HP's systems. The district court found that Apple had licensed Microsoft to use certain elements, so infringement could not be based on licensed similarities. The court also found that unlicensed similarities arose from common ideas or their logical extensions, not substantial copying of Apple's expression. Therefore, the court ruled against Apple's infringement claims.