What Are Patents?

by Grygor Scott

Article I of the U.S. Constitution empowers the federal government to grant patents to “promote the progress of science and the useful arts.” A patent is a property right that enables an inventor to prevent others from using his invention for a limited time. In essence, it gives the inventor a monopoly and the exclusive rights to sell, use, or license the invention. To receive a patent, the inventor must publicly disclose how the invention works. By providing legal protection to new inventions, patents help encourage investments in research and development without fear that another will steal their hard work.

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Subject Matter

Inventors can patent a wide range of inventions. An invention can be a process, machine or manufactured article. Original, ornamental designs for manufactured items may also be patented. Inventors may patent new and distinct types of plants that have been reproduced asexually. On the other hand, abstract ideas, mathematical formulas and naturally occurring substances are examples of things that cannot be patented.


Under U.S. patent laws, a process, machine or manufactured item must be useful to be patented. The invention must have a real-world function. This requirement does not apply to design or plant patents. To qualify for a patent, an invention cannot be substantially similar to any existing invention. The U.S. Patent and Trademark Office also will not approve a patent for an invention that would be obvious to an average scientist, engineer or other person skilled in the invention’s field. Inventions that combine well-known elements often do not satisfy this requirement.

Application Process

To receive a patent, an inventor must submit a detailed patent application to the PTO. The application must demonstrate that the invention satisfies the legal requirements for a patent. If a patent examiner approves a patent application, the PTO issues the inventor a patent certificate.

A Patent’s Scope

The key part of a patent application -- the claim -- establishes the boundaries for an approved patent. The claim provides a precise statement of the invention’s scope. It lets the public know exactly what the patent protects.

Legal Impact

A patent enables an inventor to prevent others from making, using or selling his patented invention during the term of the patent. The terms for patents range from 14 to 20 years. Patent owners protect their patent rights through lawsuits. A patent owner can sue anyone who makes, uses or sells his invention without permission for patent infringement. Although a patent is presumed to be valid, defendants in infringement cases often seek to convince a court that the PTO erred in granting the patent by arguing that the inventor’s patent does not meet one of the legal requirements for a patent.


When a patent's term ends, the property rights it grants expire. The invention enters the public domain, which means that anyone can make, use or sell the invention.