Patent
- This article relates to the intellectual property right. A land grant is also called a patent.
A patent is a set of exclusive rights granted by a state to a person for a fixed period of time in exchange for the regulated, public disclosure of certain details of a device, method, process or substance (known as an invention) which is new, inventive and useful.
The term "patent" originates from the Latin word patere which means "to lay open" (ie. make available for public inspection) and the term letters patent, which originally denoted royal decrees granting exclusive rights to certain individuals or businesses.
Economic rationale and criticisms
There are two primary justifications for granting patents. First, in accordance with the original definition of the term "patent," it is argued that awarding patents facilitates and encourages disclosure of innovations into the public domain for the common good. Without patent protection, an inventor may prefer to keep her invention a secret. Disclosure of an invention allows other inventors to improve upon it and patent their improvements. Furthermore, when a patent's term has expired, the public record insures that the patentee's idea is not lost to mankind.
Second, it is broadly believed that patent protection incentivizes economically-efficient research and development (R&D). Many corporations have annual R&D budgets of hundreds of millions or even billions of dollars. In a society without patents, it is conceivable that each corporation would lower or eliminate R&D spending, because each could reap what another had sown. This second justification closely parallels fundamental arguments underlying traditional property rights--who would build a house if another could freely occupy it?
However, there are compelling arguments in opposition to patent rights. Most fundamentally, granting a patent confers a monopoly of sorts upon an owner, because he may legally exclude competitors from using or exploiting the invention (though strictly speaking, the word "monopoly" requires that there is no viable alternative in the marketplace). In this way, patent rights differ from traditional property rights--building a house does not prevent one's neighbor from building a house, but patenting an invention bars anyone in the country of filing from producing the invention for the term of the patent. Indeed, patents have historically been granted by sovereigns to non-inventing parties in favor merely so they could profit from monopoly power. The stifling of competition due to patent rights may result in higher prices, lower quality, and shortages--characteristic problems with monopolies.
A more subtle problem with patent rights was put forth by law professors Michael Heller and Rebecca Eisenberg in a 1998 Science article. Building from Heller's theory of the tragedy of the anticommons, the professors postulated that useful innovations that build on earlier patented inventions can be inhibited by the high transaction costs from negotiating with the earlier patentees. According to Heller and Eisenberg, intellectual property rights may become so widely fragmented that, effectively, no one can take advantage of them. As one potential example, the professors identify therapeutic proteins and genetic diagnostic tests that would require the use of numerous patented gene fragments. In analogy to traditional property rights, it would be as if six different parties owned a house's two bedrooms, living room, kitchen, dining room, and bathroom--the utility of the house would be wasted until the parties could negotiate an arrangement in which one party owned the entirety.
Because of the difficulty in balancing the benefits and drawbacks of patent grants, there is ongoing debate over the extent to which patent protection should be conferred. This controversy is manifested in the ways different jurisdictions decide whether to grant patents. But recent years have seen a global embrace and augmentation of patent protection, as evidenced by the WTO Agreement on Trade-Related Aspects of Intellectual Property Rights (TRIPs).
Legal implementation
A modern patent provides the right to exclude others from making, using, selling, offering for sale, or importing the patented invention. Generally, patents are enforced only through civil lawsuits. Patent licensing agreements are effectively contracts in which the patent owner (the licensor) agrees not to sue the licensee for infringement of the licensor's patent rights. Governments typically reserve the right to suspend or cancel a patent at will.
A patent application, for a utility patent in the United States (as opposed to a design patent), must explain how to practice (i.e., make and/or use) the invention(s) and must also include claims that particularly point out the invention(s) and define the scope of the subject matter for which exclusive rights are sought by the patent applicant. The exclusive rights are limited to the subject matter encompassed by the patent's claims. 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, comprising approximately 10-15% ammonia, ..."
- "A method for computing future life expectancies, the method comprising gathering personal data including X, Y, Z, ..."
Each word of a claim is considered an "element" or "limitation" of the claim. In order to exclude someone from using your patented invention in a court, you will have to demonstrate to the court that what the other person is using is included within the scope of at least one claim of the patent.
For this reason, it is more valuable to obtain patent claims that include the absolute minimal set of limitations that differentiate a new invention over what came before. While the United States is moving towards more rigid claim interpretations, "equivalents" of claim elements or limitations may be permitted in determining patent infringement. The practice elsewhere in the world differs.
Example
If an inventor takes an existing patented mouse trap design, adds a new feature to make an improved mouse trap, and obtains a patent on the improvement, he or she can legally build his or her improved mouse trap only with permission from the patent holder of the original mouse trap, assuming the original patent is still in force.
On the other hand, the owner of the improved mouse trap can exclude the original patent owner from using the improvement. Under these circumstances, patent owners sometimes engage in cross-licensing agreements.
Governing laws
Although patents are fundamentally territorial in their nature, there are currently a number of significant international treaties governing some important aspects of patent law.
The most universal of these is the WTO TRIPs Agreement, to which almost all countries are a party. The United States, the countries of the European Union, and Japan, are parties to all of the significant treaties. This has led to significant harmonization of patent law worldwide, particularly in the last decade of the 20th century and continuing into the 21st.
Despite recent harmonization, the United States patent laws are unique in several significant respects. The biggest difference is that, if two people apply for a patent on the same invention, the US system awards the patent to the "first to invent", whereas in the rest of the world the "first to file" is awarded the patent. A contest between different inventors over priority is called "interferences". Another unique aspect of U.S. patent law is that an inventor has a one-year grace period after publication or sale to file a patent application, whereas in most other countries patent rights are lost if an application is not on file when a public disclosure, publication or sale takes place.
As mentioned above, patents are territorial in nature. Thus, patent protection in multiple countries requires separate filings of patent applications in each country, or region, where protection is sought. The Patent Cooperation Treaty (PCT), however, allows applicants to initially file a single international application, which later can be entered into separate countries or regions. Similarly, within Europe, a single patent application procedure is available through the European Patent Office, but successful applications result in multiple patents (up to 36) rather than a single European-wide patent. Such a European-wide unitary patent, or "community patent", has been the subject of discussion at the EU level since the 1970s, with no result so far.
Many of the international treaties are designed to afford some recognition of filing dates to patent applications previously filed in another country. In this respect, the most important treaty is the Paris Convention, dating back to 1883. Typically, inventors are allowed one year (the priority year) from the date of their filing (in a first country) to file the application in other countries.
The authority for patent statutes in different countries varies. In the United States, the Patent and Trademark Office gets its authority from statutes in Title 35 of the United States Code, which in turn is based on Article One, Section 8 of the U.S. Constitution.
Patent prosecution
Typically, an application for a patent is prepared by a professional agent known as a patent attorney or patent agent, who files the application with a patent office. The person applying for a patent generally does not need to be the inventor who created or authored the invention. However, in the United States a patent application must be filed in the name of the actual inventor or inventors, although the application can be assigned to another party, such as the employer of the inventor.
At the patent office an examiner will consider the invention's patentability and whether it is otherwise eligible for grant. The entire legal process of examination and obtaining grant is called patent prosecution.
Some countries do not formally review patent applications while others accept the determination of other patent offices. For example, some smaller countries, such as Belgium and the Netherlands [1] grant a patent almost automatically or with minimal examination. This may be contrasted with the strict requirements of the United States Patent and Trademark Office, the Japanese Patent Office and the European Patent Office.
The patent prosecution process typically involves:
- Filing a patent application by inventor or applicant.
- Formalizing of application (signatures by inventors or applicant), often filed at the same time as the application.
- Establishing of a prior art search report by the patent office.
- 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.
- Review by the examiner or the Examining Division, including communication with applicant to modify the claim language, if needed.
- Grant of the patent (if it the patentability criteria are met) and publication of the issued patent.
- Opposition period, during which anybody (e.g., other companies) can challenge the patent grant. This is not applicable for the US where other procedures are available, namely the reissue and reexamination procedure. In several countries, oppositions can be filed before the grant of the patent.
The specifics of the examination process include:
- Verifying that claims are for a patentable subject matter.
- Ensuring unity of invention, since each patent application can only be for one invention (called "restriction" practice in the United States).
- Formalities. Ensure that the drawings, description, and claims meet all formal requirements.
- Utility or industrial applicability.
- Novelty (newness)
- Non-obviousness or inventive step.
Different patent systems use different terms and different standards for these concepts, of which the most important probably are: patentable subject matter, novelty, non-obviousness and sufficient disclosure.
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).
Under US law, a claimed invention is deemed useful if, at the time of filing, it is capable of providing some identifiable benefit (to a person of ordinary skill in the art of the invention). The benefit must be specific, substantial, and practical.
Generally speaking, there are three broad categories of patentable subject matter: processes, machines and articles of manufacture and use.
A process could be a method for making something, a method for using something, or a method for doing something. Processes include business methods, most software, medical techniques, sports techniques and the like. Machines include devices and apparatuses. Articles of manufacture include mechanical devices, electrical/electronic devices and compositions of matter such as chemicals, medicines, DNA, RNA, etc.
However, laws of nature, physical phenomena, and abstract ideas are not patentable. Software inventions implementing algorithms are not patentable for this reason unless it produces a "useful, concrete, and tangible result" (US law) or technical effect (European law). The US standard for the patentability of software is more liberal than that in Europe. Japanese patent law lies between the US and Europe.
The patentability of software (and business methods) is quite controversial from a global perspective. Case law in the United States permits patents for software and business methods. Yet computer programs as such are 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, medical treatment techniques, and genetic sequences 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 exclude physicians from performing the surgical method.
Novelty
Novelty relates to whether something existed before its invention by the applicant or was disclosed to the public before the patent application's filing date. For public disclosures of the invention by the inventor, the United States and Canada permit a one year grace period, but most other countries provide no grace period, instead requiring "absolute novelty".
An invention is not novel if there is a previously existing or disclosed device or process that includes all of the elements of the claimed invention. Identifying such "prior art" by the patent examiner is accomplished by a search of literature (technical journals, published patent applications and issued patents, etc.) that predate the filing date of the particular patent application.
Non-obviousness or inventive step
- Main articles: Non-obviousness (patent) and Inventive step.
Even if an applicant's claim for an invention is novel (i.e. not taught by a single prior art reference), a patent can still be denied to the applicant if the claimed subject matter would have been obvious to someone else skilled in the technical field of the invention. The purpose of forbidding patents on obvious technologies is to prevent a person from obtaining exclusive rights to what is effectively already 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 having 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 patent applications in the United States, Europe and Japan 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 can receive patents.
Generally, the patent laws make it difficult for patent examiners to employ hindsight reasoning in rejecting a claim as obvious, by requiring some teaching that would motivate a person of ordinary skill in the art to modify the technology found in the prior to arrive at the claimed invention. In the United States, objective evidence or secondary considerations of non-obviousness can overcome a proper obviousness rejection. Such secondary considerations can 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 that one of ordinary skill would make that combination.
The threshold for the obviousness or inventive step standard can be particularly ambiguous 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 genus, should the inventor be entitled to a patent on the entire genus? Further, 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 results that are unexpectedly different from those 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). Can someone else then obtain a patent on an "improved" quicksort suitable for use on any partially ordered set (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.
Finally, in spite of all precautions, some patents still give a general impression of triviality. An example is given by the "combover" patent (U.S. patent 4,022,227, filed December 1975), which has also been awarded the 2004 Ig Nobel Prize in engineering for its apparently unintentional ridiculousness.
Term of patent
As TRIPS agreement declares, the maximum term of an issued patent is 20 years from earliest claimed filing date. In the United States, for applications filed after to June 8, 1995, the patent term is 20 years from the earliest claimed filing date (see also: Term of patent in the United States).
Also, in several countries there are multiple types of patents, and the 20 year term frequently only applies to 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 14 years from its issue date.
Example
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 20 years from the earliest claimed priority: January 1, 2016.
Miscellaneous
While a patent grants an exclusive right on the invention claimed, many national laws provide for special rules on granting compulsory license to requesting third parties when the invention is not put into to practice within a specified amount of time or is put into practice in a manner that is deemed to be insufficient for the needs of the Country. In practice, obtaining a compulsory license is not easy.
Secrecy provisions are also present in many national laws in case the invention for which a patent is filed is deemed to have military interest.
A patent might also be seized by the State under grounds of public utility. For example, during the 2001 anthrax attacks, it was rumoured that the US had considered seizing the patent on the Cipro antibiotic from the Bayer Corporation. However, the anthrax attacks did not continue and the patent was not seized.
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 Italy.
The first patent law was a Venetian Statute of 1474 in which the Republic of Venice issued a decree by which new and inventive devices, once they had been put into practice, had to be communicated to the Republic in order to obtain legal protection against potential infringers. England followed with the Statute of Monopolies in 1623 under King James I. Prior to this time, the crown would issue letters patent providing any person with a "monopoly" to produce particular goods or provide particular services. The first of them was granted by Henry VI in 1449 to a Flemish man a 20 year monopoly on the manufacture of stained glass.
This was the start of a long tradition by the English Crown of the granting of "letters patent" (meaning 'open letter', as opposed to a letter under seal) which granted "monopolies" to favoured persons (or people who were prepared to pay for them). This became increasingly open to abuse as the Crown granted patents in respect of all sorts of known goods (salt, for example). 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. After public outcry, James I was forced to revoke all existing monopolies and declare that they were only to be used for 'projects of new invention'. This was incorporated into the Statute of Monopolies in which Parliament restricted the crown's power explicitly so that the King could only issue letters patents to the inventors or introducers of original inventions for a fixed number of years.
In the reign of Queen Anne the rules were changed again so that a written description of the article was given. Section 6 of the Statute refers to "manner[s] of new manufacture... [by] inventors", and this section remains the foundation for patent law in New Zealand and Australia. The Statute of Monopolies was later developed by the courts to produce modern patent law; this innovation was soon adopted by other countries.
The Patent Commission of the U.S. was created in 1790. Its first three members were Secretary of State Thomas Jefferson, Secretary of War Henry Knox, and Attorney General Edmund Randolph. On July 31, 1790 inventor Samuel Hopkins of Pittsford, Vermont became the first person to be issued a patent in the United States. His patented invention was an improvement in the "making of Pot Ash by a new apparatus & process". The earliest patent law required that a working model of each invention be produced in miniature.
The Patent Law was revised for the first time in 1793. It adopted a simple registration system where a patent would be granted for a $30 fee. The Patent Board was replaced by a clerk in the Department of State. James Madison, Secretary of State, created a separate Patent Office within the State Department and he appointed Dr. William Thornton as its first superintendent in May 1802. On May 5th, 1809 Mary Dixon Kies became the first woman to be awarded a U.S. patent. Later, in 1810, the Patent Office moved from the Department of State to Blodgetts Hotel. In the same year, they opened the patent model storage to the general public.
The first 10,000 patents issued by the USPTO from July 1790 to July 1836 were perished in a fire in December 1836. About 2800 of them were later recovered. But the majority of them are still missing. The recovered patents are now called X-Patents because their patent numbers end with an "X."
Patent models
One of the most interesting early features of the U.S. patent system was the requirement of patent models. A patent model was a scratch-built miniature model no larger than 12" by 12" that showed how the patent works. Since most early inventors were ordinary people without technological or legal training, it was difficult for them to submit formal patent applications, due to the required small-scale models. However, to some degree, it was beneficial for these amateur inventors to submit a model. This is because their inventions might not be fully comprehended otherwise.
Patent models were required since 1790. The Congress of the U.S. abolished the legal requirement for them in 1870. The U.S. Patent Office kept this requirement until 1880. However, some inventors still willingly submitted models at the turn of the 20th century.
A working model, or other physical exhibit, may be required by the U.S. patent office if deemed necessary. This is not done very often. A working model may be requested in the case of applications for patent for alleged perpetual motion devices (Source: USPTO web site).
Quotes
- 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.
- Certainly an inventor ought to be allowed a right to the benefit of his invention for some certain time. Nobody wishes more than I do that ingenuity should receive liberal encouragement. In the arts, and especially in the mechanical arts, many ingenious improvements are made in consequence of the patent right giving exclusive use of them for fourteen years.
- Before then [the adoption of the United States Constitution], any man might instantly use what another had invented; so that the inventor had no special advantage from his own invention. The patent system changed this; secured to the inventor, for a limited time, the exclusive use of his invention; and thereby added the fuel of interest to the fire of genius, in the discovery and production of new and useful things.
- -Abraham Lincoln, Second lecture on discoveries and inventions, February 11, 1859 [2] (from page 356b) [3]
- In the field of industrial patents in particular we shall have seriously to examine whether the award of a monopoly privilege is really the most appropriate and effective form of reward for the kind of risk bearing which investment in scientific research involves.
- -F.A. von Hayek, Individualism and Economic Order, 1948
- A country without a patent office and good patent laws is just a crab and can't travel any way but sideways and backwards.
- -Mark Twain, A Connecticut Yankee in King Arthur's Court, 1889.
Related articles
Legal concepts
Assignor estoppel -- Claim -- Defensive publication -- Disclaimer -- Doctrine of equivalents -- Essential patent -- Exhaustion of rights -- First to file -- First to invent -- Industrial applicability -- Interference proceeding -- Inventive step -- Inventor -- Letters patent -- Non-obviousness -- Novelty -- On-sale bar -- Patent family -- Patent infringement -- Patent misuse -- Patent pending -- Patent pool -- Patentability -- Person having ordinary skill in the art -- Petition to make special -- Prior art -- Prosecution history estoppel -- Provisional rights -- Reasonable and Non Discriminatory Licensing -- Reduction to practice -- Research exemption -- Submarine patent -- Sufficiency of disclosure -- Supplementary protection certificate -- Term of patent -- Unity of invention -- Utility
Special types of patents and patent applications
Biological patent -- Business method patent -- Chemical patent -- Design patent -- Gebrauchsmuster -- Kokai -- Kokoku -- Patent application (see also: Continuing patent application (incl. continuation, divisional and cip) -- Provisional application) -- Software patent (see also: List of software patents -- Software patent debate -- Software patents under the European Patent Convention -- Software patents under the Patent Cooperation Treaty -- Software patents under TRIPs Agreement -- Software patents under U.S. patent law) -- Utility model
Organizations and patent offices
Main articles: intellectual property organization and patent office.
African Regional Intellectual Property Organization (ARIPO) -- Canadian Intellectual Property Office (CIPO) -- Eurasian Patent Organization (EAPO) -- European Patent Organisation (EPO or EPOrg) (incl. European Patent Office) -- Organisation Africaine de la Propriété Intellectuelle (OAPI) -- United Kingdom Patent Office -- United States Patent and Trademark Office (USPTO) -- World Intellectual Property Organization (WIPO)
Treaties, conventions and other legal texts and frameworks
Agreement on Trade-Related Aspects of Intellectual Property Rights (TRIPs Agreement) -- American Inventors Protection Act (AIPA) -- Budapest Treaty -- Community Patent (proposed) -- EU Directive on the Patentability of Computer-Implemented Inventions (proposed, then rejected) -- EU Directive on the Patentability of Biotechnological Inventions -- European Patent Convention (EPC) -- European patent law -- European Patent Litigation Agreement (EPLA) (proposed) -- London Agreement (concluded but not in force yet) -- Paris Convention for the Protection of Industrial Property -- US Patent Reform Act of 2005 -- Patent Cooperation Treaty (PCT) -- Patent Law Treaty (PLT) -- Substantive Patent Law Treaty (SPLT) (proposed) -- Statute of Monopolies 1623 -- Strasbourg Convention -- United States patent law
Other
Chartered Institute of Patent Agents (CIPA) -- esp@cenet -- Industrial design rights -- Industrial property -- INPADOC - Intellectual property -- International Patent Classification (IPC) -- List of top United States patent recipients -- Patent attorney -- Patent clerk -- Patent model -- Patent troll -- X-Patent
External links
- Patents in Webster's Dictionary - the Rosetta Edition
- IPFrontline™ PatentCafe's Intellectual Property & Technology Magazine
- National Inventor Fraud Center - Information about the invention process and invention marketing companies.
- Patent Law Portal - Patent Law News, Articles and Resouces
- mp3board.com - News site which aggregates patent news (and other IP news).
- Paper: Exceptions to exclusive rights and compulsory licenses(incl. experimental and private use)
- Some thoughts on how the patent process may be improved
- Brown & Michaels, PC - General information about intellectual property, including a patent FAQ
- US and Foreign Patent practices (and law changes)
- Patent Information - Information on Patents and Copyrights
- IP Newsflash recent case law and developments regarding patents
Patent Office Web sites and other regional info
- IP Australia incorporates the Patent, Designs and Trade Marks offices
- U.S. Patent and Trademark Office
- PatentHunter - Desktop software for searching and downloading patents from the USPTO and EPO websites.
- Canadian Intellectual Property Office
- Japan Patent Office
- Korean Intellectual Property Office
- European Patent Office
- Int. Patent & Trademark Attorneys The Netherlands
- UK Patent Office
- NKPAL's IPRs Division - IPRs information and Patent filing in India.
- World Intellectual Property Organisation
- Innovation and patent information in Italy
- http://www.patentlesson.com
Patent organizations
Patent competitive intelligence
Patent discussion
- Quotes from Fritz Machlup report 1958
- Netflix patent buys time - shumans.com article, June 29, 2003. [Related to patent number US 6584450]
- IEEE spectrum: Patent Prescription - A radical cure for the ailing U.S. patent system
- Medical Patents: Developing Countries Suffer the Most
Patent searches and downloads
- pat2pdf.org - Free lookup and download of U.S. patents in PDF form
- FreePatentsOnline.com - Free US patent searching database and list of funny patents.
- The Guide to Downloading Copies of Patents from Internet
- Delphion IP Research
- Free US and Worldwide Patent PDFs - Download patents for free.
- search4ip - Free patent search.
- PatentMatic - Free patent downloads (US, European & others).
- PatentCafe's International Patent Database with Semantic / Natural Language Search Engine