In trademark law, the functionality doctrine prevents manufacturers from protecting specific features of a product by means of trademark

Trademark

A trademark, trade mark, or trade-mark is a distinctive sign or indicator used by an individual, business organization, or other legal entity to identify that the products or services to consumers with which the trademark appears originate from a unique source, and to distinguish its products or...

 law. This separates trademarks from patent

Patent

A patent is a form of intellectual property. It consists of a set of exclusive rights granted by a sovereign state to an inventor or their assignee for a limited period of time in exchange for the public disclosure of an invention....

s — trademarks serve to protect a firm

Business

A business is an organization engaged in the trade of goods, services, or both to consumers. Businesses are predominant in capitalist economies, where most of them are privately owned and administered to earn profit to increase the wealth of their owners. Businesses may also be not-for-profit...

's reputation

Reputation

Reputation of a social entity is an opinion about that entity, typically a result of social evaluation on a set of criteria...

 and goodwill, whereas patents serve to protect processes, machine

Machine

A machine manages power to accomplish a task, examples include, a mechanical system, a computing system, an electronic system, and a molecular machine. In common usage, the meaning is that of a device having parts that perform or assist in performing any type of work...

s, and material invention

Invention

An invention is a novel composition, device, or process. An invention may be derived from a pre-existing model or idea, or it could be independently conceived, in which case it may be a radical breakthrough. In addition, there is cultural invention, which is an innovative set of useful social...

s.

If a feature gives a producer a competitive advantage which is not related entirely to its function as a brand

Brand

The American Marketing Association defines a brand as a "Name, term, design, symbol, or any other feature that identifies one seller's good or service as distinct from those of other sellers."...

identifier, then it cannot be trademarked. The rationale behind this doctrine is that product markets would not be truly competitive if newcomers could not make product with a feature that consumers demand.