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A patent is a set of exclusive rights granted by the government to an inventor for a limited amount of time (normally 20 years). The term's origin falls out from the term to patent which means to lay open (to public[?] inspection) and the term letters patent, which originally denoted royal decrees granting monopoly privilege to certain businesses. Per the word's original definition, the social goal of patents is to induce the inventor to disclose knowledge for the advancement of society in exchange for a limited period of exclusivity.

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Rights granted and rights not granted A modern patent is a right to exclude others from making, using, selling, offering for sale, or importing the invention. Generally, patents are enforced only through private actions; through civil lawsuits or licensing agreements[?]. Governments typically reserve the right to suspend a patent at will.

An application for a patent (other than a design patent) must explain how to make and use the invention and must also include "claims" that particularly point out what is the invention. The exclusive right is limited to the claimed invention, more specifically to the patent claims that appear at the back of most printed patent publications. The patent claims are typically of the form of a long sentence, e.g. "An apparatus for catching mice comprising, a base member for placement on a flat surface, a spring member...", "A chemical for cleaning windows comprised of 10-15% ammonia, ...", "A method for computing future life expectancies, the method comprising gathering personal data including X,Y, Z, ...", etc.

Claim language formats and practices vary widely between different countries. Each of the listed items is an element of the claim. In order to exclude someone from using your invention in a court you will have to demonstrate to the court that what the other person is using is identical to the claimed invention. (Note, while the United States is moving towards more rigid claim interpretations and generally issued patents have a large number of claims, the practice elsewhere in the world differs.)


If an inventor takes an existing patented mouse trap design and modifies it to make an improved mouse trap and obtains a patent on the improvement, she cannot build her improved mouse trap without permission (or risking being sued) from the patent owner on the original mouse trap. However, if the original patent owner tried to copy the inventor's improvement, she could sue them to exclude them from using her patented invention without permission.

Continuing the example though, if the inventor's improved mouse trap patent requires a guillotining member, but the original manufacturer copies other aspects of the improvement. The inventor may not be able to exclude the manufacturer from using those other improvements.

For this reason, it is important, especially in the United States, that the patent claims include the absolute minimal set of items that differentiate a new invention over what came before. Dependent claims can be used to describe additional variations and features.

Governing laws At this point there are a number of significant international treaties governing patent law and the United States, European Union, and Japan, are parties to the significant ones. This has lead to significant harmonization of patent law worldwide particularly in the last ten to fifteen years. Procedurally, the United States system is perhaps one of the more unusual although some recent changes have brought the United States' system further into line with other major patent systems. The biggest difference that remains is the US system of giving the patent to the "first to invent", in the rest of the world the "first to file" gets the patent. However, in contests between different inventors over priority (called "interferences"), the second one to file has the burden of proof and usually loses such contests.

Patent grants are territorial in nature. Thus, patent protection in multiple countries require separate filings of patent applications in each country, or region, where protection is sought. Within Europe, it is possible to apply for a patent with the European Patent Office; but these are not true regional patents, see Community Patent for discussion.

Many of the international treaties are designed to afford some recognition of filing dates to patent applications filed in one country. Typically, inventors are allowed one year from the date of their filing in their home country to file the application abroad, frequently called national stage filing. Systems such as the PCT[?] allow inventors a cost effective way to further delay national stage filings.

The authority for patent statutes in different countries varies. In the United States, the authority is rooted in Article One, Section 8 of the United States Constitution. In other countries, the origin may be a statute or other law or rule.

Examination process and procedure Typically, an application for a patent is examined before a patent is issued or granted for an invention. That is to say, the application is reviewed by a patent examiner for patentability.

Some countries do not formally review patents and others will accept the judgment of other patent examining authorities. For example, some smaller countries, such as Belgium, will grant a patent automatically or with minimal examination if a patent has been granted on the same invention in the United States, European Union, or Japan.

A typical examining procedure is:

  1. Filing a patent application by inventor or applicant.
  2. Formalizing of application (signatures by inventors or applicant), often filed at the same time as the application.
  3. Initial Publication at 18 months from earliest claimed filing date. US applicants can request non-publication if the application is not filed outside the United States.
  4. Review by Examiner, including back and forth negotiation with applicant to narrow/modify the scope of the claims.
  5. Publication for opposition, period of time in which other companies and inventors can challenge the proposed patent grant. (Not in the US)
  6. Grant if standards for patentability met.

The specifics of the review process include:

  1. Verifying that claims are for a legal subject matter for a patent
  2. Unity of invention, since each patent application can only be for one invention. (Called "restriction" practice in the United States.)
  3. Formalities. Is the claim grammatical, properly drawn and unambiguous?
  4. Utility or industrial applicability.
  5. Novelty (newness)
  6. Non-obviousness or inventive step.

Different patent systems use different terms for these standards. The most important are: patentable subject matter, novelty and non-obviousness.

Patentable subject matter

The standard for what is patentable subject matter in the United States is "anything under the sun made by man" that is new (novel), useful, and non-obvious. Similar standards for patentability apply in Japan and the European Patent Office (EPO). An invention lacks utility if it does not function as described in the patent application or if it would violate accepted scientific principles. Applications for patents on perpetual motion machines generally are rejected as lacking utility.

Generally speaking, there are three broad categories: processes, machines, and articles of manufacture. Processes include algorithms, business methods, most software, medical techniques, sports techniques and the like. Machines includes devices and apparatuses. Articles of manufacture include mechanical devices, electrical/electronic devices and compositions of matter such as chemicals, medicines, DNA, RNA, etc.

Mathematical truths, however, are not patentable, and software inventions implementing algorithms are not patentable for this reason unless there is some kind of practical application (US law) or technical effect (European law). The US standard for the patentability of software is more liberal than that in European. Japanese patent law lies between the US and Europe.

Presently in 2001, the patenting of software (and business methods) is quite controversial. Case law in the United States permits software and business method patents; software as such is not patentable in Europe, although some inventions that use software can be patented in Europe.

Patents related to natural compounds (e.g. items found in rainforests) as well as medicines and medical treatment techniques are also controversial. There are significant country-by-country differences in handling these subject matters. For example, in the United States you can get a patent for a surgical method but you cannot enforce your right to exclude.


Novelty related to whether something existed before its invention by the applicant or was divulged to the public before the filing date. For public disclosures of the invention by the inventor, the United States permits a 1 year grace period, but most other countries require "absolute novelty".

An invention is not novel if there is a previously existing or divulged device or process that includes all of the essential features of the claimed invention. This is accomplished by a search of literature (technical journals, published and issued patents, etc.) that predate the filing date of the particular patent application.

This comparison is highly technical in the sense that if the patent claim requires a blade to be between "5-10 cm" and a particular reference (one piece of literature found by the examiner) speaks of using "at least 11 cm", then for the purposes of the novelty standard the reference is insufficient to show the invention is not new.


Even if an applicant's claim for an invention is technically novel (i.e. not embodied in a single existing device or process), a patent can still be denied to the applicant if the applicant's subject matter is "obvious". The purpose of forbidding patents on obvious technologies is to prevent a person from privatizing what is effectively in the possession of the public, even if documentation of the exact form of the applicant's embodiment happens to be lacking.

Accordingly, obviousness asks the question whether all previously known technology related to the invention would teach a "person of ordinary skill in the art", e.g. someone who does the type of things relating to the technical field of the invention, how to make the invention. Many applications for United States patents are initially rejected as being obvious.

The standard of obviousness and its application are more subjective and controversial than that of novelty. If the requirements are set very high, virtually nothing is patentable. Similarly if the requirements are very low, all kinds of trivial inventions receive patents. For example, a much criticized software patent of the USA, for example, is the "one click patent" awarded to amazon.com for buying products in online stores with a single mouseclick; however, invalidating prior art for this patent was uncovered in the course of Amazon's law suit against Barnes & Noble.

Generally, the patent laws make it difficult for patent examiners to employ hindsight reason in rejecting a claim as obvious, by requiring some teaching that would motivate the person of ordinary skill in the art to modify the technology found in the prior that would produce what the patent applicant claims to be an invention. In the United States, objective evidence or secondary considerations of non-obviousness include unexpected results, commercial success, long-felt need, failure of others, copying by others, licensing, and skepticism of experts.

As a practical matter, during examination the patent examiner will attempt to locate two or more references that when combined show all of the features of the claimed invention and indicate what one of ordinary skill would make that combination. Continuing the example of the claim limitation of a blade that is "5-10 cm", if a second reference were found that said something like "in many instances where long blade sizes are required smaller length blades can be used with equal efficacy", then the examiner would argue that the two references in combination teach or suggest the claimed limitation.

The threshold for the obviousness standard can be particularly frustrating in genus-species situations. For example, if an inventor finds two species of a particular genus, e.g. two particular chemical compositions out of 10,000 in the broader class, should the inventor be entitled to a patent on the entire genus? Further, what if someone has discovered the genus already, but not isolated any of the species, are the species obvious in light of the genus? Under US law, the species may still be patentable if they produce result unexpectedly different than that of other previously known members of the genus.

For example, suppose a software inventor unveils the quicksort sorting algorithm to the world but only discloses it using integers (this is the species). The next day, can someone else file a patent on an "improved" quicksort suitable for use on any set where a partial ordering can be defined (this is the genus)? Under US law, this is not a question of obviousness since a claim to the genus lacks novelty as the species is known.

Term of patent Virtually every country in the world gives a term of twenty years from earliest claimed filing date to define the term of a patent. In the United States, the patent term used to be seventeen years from issue, but the term was changed in 1995 to the twenty years from filing. The rules for patents in force and pending at the transition date are significantly more complicated but grant the patentee whichever term is longer.

Also, in several countries there are multiple types of patents, in that case, the twenty year term frequently only applies to so called utility patents and not design, petit, or other kinds of less heavily examined patents. For example, the term of a U.S. design patent, which protects the ornamental shape of objects, lasts fourteen years.


If the better mousetrap patent is filed on January 1, 1996 and is issued or granted on January 1, 2000, it will lapse twenty years from filing: January 1, 2016. However, if the inventor comes up with a second improvement and claims priority to her first patent when filing the second patent on January 1, 1998, that second patent, after grant, would lapse twenty years from the earliest claimed priority: January 1, 2016.

Early history of patents Although there is evidence suggesting that something like patents was used among some ancient Greek cities, patents in the modern sense originated in England with the Statute of Monopolies[?] in 1624 under King James I of England. Prior to this time, the crown would issue letters patent providing any person with a monopoly to produce particular goods or provide particular services. This power, which was to raise money for the crown, was widely abused, and court began to limit the circumstances in which they could be granted. Parliament eventually restricted the crown's power explicitly through the Statute of Monopolies so that the King could only issue letters patents to the inventors or introducers of original inventions for a fixed number of years. Section 6 of the Statute refers to "manner[s] of new manufacture . . . [by] inventors", and this section remains the foundation for patent law in England and Australia. The Statute of Monopolies was latter developed by the courts to produce modern patent law; this innovation was soon adopted by other countries.


If nature has made any one thing less susceptible than all others of exclusive property, it is the action of the thinking power called an idea, which an individual may exclusively possess as long as he keeps it to himself; but the moment it is divulged, it forces itself into the possession of everyone, and the receiver cannot dispossess himself of it. Its peculiar character, too, is that no one possesses the less, because every other possesses the whole of it. He who receives an idea from me, receives instruction himself without lessening mine; as he who lights his taper at mine, receives light without darkening me. That ideas should freely spread from one to another over the globe, for the moral and mutual instruction of man, and improvement of his condition, seems to have been peculiarly and benevolently designed by nature, when she made them, like fire, expansible over all space, without lessening their density at any point, and like the air in which we breathe, move, and have our physical being, incapable of confinement or exclusive appropriation. Inventions then cannot, in nature, be a subject of property.
- Thomas Jefferson

See also: law, intellectual property, chemical patent, Software patent, United States patent[?], United States Patent and Trademark Office

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