A patent consists of an abstract, a description of the invention, disclosures of prior art, drawings, and one or more claims. The claims are the only enforceable part of a utility patent, and they define the property right the patent holder owns. A patent applicant writes a claim in technical language. The claim must describe subject matter that is within the scope of patent law, is novel and is not obvious. If on analogizes a patent to real estate, the claims correspond to the boundary recited in the deed. Invasion of the boundary of a landowner's real estate is called trespass, while invasion of a patent holder's claims is called infringement.
A broadly written claim may very well be rejected by the U.S. Patent and Trademark Office, or later invalidated by a court, on the grounds of obviousness or anticipation by prior technology. A more narrowly written claim, while safer from invalidation, is the less to serve as the basis for a suit that alleges a competing technology or device infringes the claims. To infringe a patent, one must practice every element of a claim. If an alleged infringer does not practice one or more of the elements of a claim, then the patent holder cannot maintain an infringement suit.
The origin of U.S. patent law finds itself in the United States Constitution, Article I, Section 8, Clause 8, which provides that: "Congress shall have the power . [t]o promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries." Congress created a patent system to promote creativity by rewarding the inventor with a limited monopoly on using, making, and selling his or her inventions.
In exchange for the right to exclude others from using, making, or selling the invention, an inventor agrees to make public the invention. Once issued, patents become public record. Inventors must also disclose, in the patent application, the "best mode" for making or using the patented invention. Failure to do so can result in an invalid patent.
The three types of patents include utility, design, and plant patents, with utility patents being the most common. Utility patents cover industrial or technical processes, methods of doing business, and software. They also include machines, or combinations of mechanical and electrical elements, including special purpose computer systems. In addition, a utility patent covers compositions of matter, which are physical entities where the substance itself is the important element, such as chemical compositions, mixtures of ingredients and new chemical compounds. Finally, articles of manufacture, tangible, manmade or manufactured items, generally including all products not considered "machines" or compositions of matter, benefit from protection in the form of a utility patent. Utility patents also cover any improvements on the above types of patented items.
An applicant may obtain a design patents for any new, original, and ornamental design for an article of manufacture. Plant patents protect inventors who discover and asexually reproduce any distinct and new variety of plant.
For patents filed on June 8, 1995 or later, the protection lasts for 20 years from the date the patent application is filed. For patents filed prior to June 8, 1995, the term is 17 years from the date of issuance or 20 years from the date of application, whichever is longer.
To qualify for patent protection, an invention must be new, useful and non-obvious.
To qualify as new, an invention must not exist in the public domain before the patent applicant invented it. The Office will not grant a patent on an invention publicly used or on sale by anyone, including the inventor, more than one year before the inventor filed a patent application. Identical or similar inventions that others publicly disclose anywhere in the world before an inventor files the patent application, known as "prior art", may prevent the inventor from obtaining patent protection because the Office would not consider the invention novel.
An invention seeking patent protection must have some use. An applicant must, as part of the application process, disclose the utility of the invention. Usefulness does not require, however, that the invention possess commercial viability. One should note that a patent gives its owner the right to exclude others from making, using or selling the invention in the U.S. A patent does not confer the right to actually use the invention, and many times the need to employ other patented technologies or machines prevents an inventions use. In these situations, the ability to license or assign a patent can allow for a beneficial resolution of all of the patent holders.
The final requirement for patent protection is that the invention is non-obvious. Even if no particular prior art precisely anticipates an invention, it can still be "obvious" and thus barred from patent protection. The test for obviousness is whether, "[i]n light of known, similar products, processes or designs, a person of ordinary skill working in the field related to the inventor's invention [would] consider the differences between the invention and similar products, processes or designs obvious" A combination of prior art resulting in the invention may also cause the Office to find the invention obvious.