Castro v. Chicago, Rock Island & Pacific Railroad

How later courts describe this case

• “to protect consumers against deceptive designations of the origin of goods and, conversely, to enable producers to differentiate their products from those of others”
• a feature of an item may “serve simultaneously as a functional component of a product and a trademark”
• the source of the right sued upon, not the ground on which the federal jurisdiction is invoked, determines whether federal or state law applies
• ornamental features may fill a consumer need without serving as a trademark even though such features may be nonutilitarian
• defendant permitted to manufacture jewelry bearing plaintiffs mark