Roots of the U.S. Patent Law are embedded in our Constitution:
"The Congress shall have power . . . to promote the progress of science and useful arts, by securing for limited time to authors and inventors the exclusive right to their respective writings and discoveries." (Emphasis added)
A patent is granted to an inventor to exclude others from making, using, offering for sale, or selling the invention in the United States, or importing the invention into the United States. These rights are based on "Quid Pro Quo" basis –meaning "something for something." Issued patents are published documents with a full and lucid disclosure of the invention. A patent thus enhances the wealth of public knowledge and "promotes the progress of science and useful arts." Abraham Lincoln, originally a successful corporate lawyer before he entered active politics, praised U.S. Patent Law as "adding fuel of interest to the fire of the genus."
Unlike other intellectual properties, such as Trademark and Copyright, patent rights are not enforceable unless a patent is issued upon filing and prosecution of a patent application. A patent right is not an "affirmative right to make, use, offer for sale, sell, or to import an invention into the United States," but rather a "negative right" to exclude others from performing those acts.
Grant of a patent does not mean a government certification that the patented invention really works, is safe, or is beneficial to the society. A utility patent issued in United States is valid for a period of 20 years from the date of patent application (unless challenged in courts for validity), and is enforceable only in U.S.
What is patentable?
"Whoever invents or discovers any new and useful process, manufacture, or composition of matter or any new and useful improvement thereof, may obtain a patent therefor, subject to the conditions of this title."
In the famous State Street case,  the Court of Appeals for the Federal Circuit pointed out that the repetitive use of the expansive term "any" in § 101 confirms Congress "did not intend to place any restriction on the subject matter for which a patent may be obtained, beyond those specifically recited in
§ 101." Going back in history, we learn that the definition of patentable subject matter has remained almost unchanged since Thomas Jefferson defined it in 1793 as,
"any new and useful art, machine, manufacture, or composition, or any new and useful modification [thereof]."
In 1952, when the new patent law was codified, the only change was that the word "art" employed by Jefferson, was replaced by the word "process." The act embodies Jefferson’s philosophy that
"Ingenuity should receive a liberal encouragement." 
In subsequent court decisions, notably Diamond v. Chakraborty,  the Supreme Court has acknowledged that the Congress intended § 101 to "include anything under the sun that is made by man." Later in Diamond v. Diehr, Justice Rehnquist stated:
"Although the term "process" was not added to 35 U.S.C. § 101 until 1952, a process has historically enjoyed patent protection because it was considered a form of "art" as that term was used in the 1793 Act." In defining the nature of a patentable process, the Court further stated: "That a process may be patentable, irrespective of the particular form of the instrumentalities used, - - - . A process is a mode of treatment of certain materials to produce a given result. It is an act, or a series of acts, performed upon the subject-matter to be transformed and reduced to a different state or thing. If new and useful, it is just as patentable as is a piece of machinery." 
Patent law does not make a distinction between living and inanimate things; so long as it is made by humans. So a genetically altered mouse, a cloned animal and a living bacteria, if produced with methods developed by humans, are "patentable subject matter." However three exceptions to patentability under 35 U.S.C. § 101 are identified by courts; and these are laws of nature, physical phenomena, and abstract ideas.
There are some other exceptions too, such as literary, dramatic, musical, and artistic works which can be protected under copyright laws.
Also, inventions that are against public policy and morality or inventions for the sole purpose of a criminal use are not patentable. One other exception to patentability is established by The Atomic Energy Act of 1954, prohibiting patent to an invention using special nuclear material or atomic energy for atomic weapons. A new mineral discovered deep in the earth, or a rare plant growing in rain forest- yet unknown to humans, are natural phenomena, which cannot belong to man, and therefore are not patentable, But several hundred patents on computers, most of them new improvements on earlier computer inventions, were patented because "new improvement," is defined as patentable in statute 35 U.S.C. § 101. Discovery of the Formula E=mc2 by Einstein and the discovery of gravity by Newton are however not patentable being laws of nature.
Business method claims, earlier considered "un patentable," by then-prevailing common misconceptions, are now clearly patentable under § 101 if they meet certain conditions. In the landmark case of State Street Bank & Trust Co. v. Signature Financial Group, Inc.,  the United States Court of Appeals for the Federal Circuit held that "the transformation of data, representing discrete dollar amounts, by a machine through a series of mathematical calculations into a final share price, constitutes a practical application of a mathematical algorithm, formula, or calculation, because it produces "a useful, concrete and tangible result, and falls within statutory subject matter (emphasis added). And "it is of little relevance whether claim 1 is directed to a machine or process, as long as it falls within at least one of the four enumerated categories of patentable subject matter, "machine" and "process’ being such categories."
Business methods embrace a wide range of activities including methods of buying and selling, marketing techniques, financial schemes, and improvements on these, which were earlier considered unpatentable subject matter, are not so any longer just for being "business method claims." They might be patentable if they pass the test of patentability under § 101, and other relevant tests as per the patent laws and procedures.
Jeff Bozo, et al. of Amazon.com patented a method and system for placing a purchase order on line via a network by a method.  The holding company of Priceline.com patented its internet version of an ancient auction technique, the name-your-price "reverse auction."  Flood gates are now open, and the Business Method patents are the fastest growing patent category, some of these patents dazzle us with the brilliance of future technology (Social dilemma software for evaluating online interactive societies),  and others baffle us with the triviality (method of bra size determination by direct measurement of breast). 
Patentability and the loss of rights
Having first established that the invention is useful and within the domain of "patentable subject matter" as defined in 35 U.S.C. § 101, the patent application needs to pass the test of novelty, and nonobviousness, under § 35 U.S.C. § 102 and 35 U.S.C. §103 respectively. Novelty requirements are defined under § 102 in paragraphs (a) to (f), by enumerating about 16 events that can defeat the patentability.
Novelty is checked by comparing the claimed invention to the "prior art," which includes:
- prior patents/publication (and even a prior patent application in some cases)
-prior public use
-prior commercial offer to sell, or prior sale
If the invention was known or used by another in United States, or described in a patent or printed publication anywhere in the world, it will not be patentable under § 102(a). In order to encourage prompt disclosure of an invention, while still allowing an inventor reasonable time to ascertain marketability, the U.S. Patent Office allows, under § 102(b), the inventor a grace period of one year (statutory time limit) for filing the patent application, after sale or use of the invention in United States, or publication or patent of the same anywhere in the world. Filing of a foreign application (more than a year before a U.S. filing), which matured in a patent, also disallows patentability of U.S. application under § 102(d). Whereas
§ 102(a) and § 102(b) identify patent and printed application as prior art, § 102(e) goes a step further; and establishes even an earlier filed patent application as a prior art under certain circumstances.
The United States is probably the only country awarding priority for grant of patent to the "first person to invent," rather than to the "first person to file," even if this first inventor is not the first filer of patent application. U.S. patent law under § 102(g), defines the criteria that are used to determine the first inventor.
As a U.S. patent is granted to an inventor, § 102(c) prohibits grant of patent to one who after inventing abandoned the invention; and also disallows a patent to one who "did not himself invent the subject matter sought to be patented per se 102(f)." Under§ 102(f) a contributor to invention, irrespective of the contributor’s share, needs to be added as joint inventor in the patent application to avoid loss of patent rights.
Even if an invention is a "statutory subject matter," and is new and useful, it must not be close or obvious to something already existing at that time. 35 U.S.C. § 103(a) states:
"A patent may not be obtained though the invention is not identically disclosed or described as set forth in section 102 of this title, if the differences between the subject matter sought to be patented and the prior art are such that the subject matter as a whole would have been obvious at the time the invention was made to a person having ordinary skill in the art to which said subject matter pertains. Patentability shall not be negatived by the manner in which the invention was made."
Like novelty, the obviousness is tested by comparing the claimed invention to the "prior art."
The patentability tests, supported by an examiner’s search on relevant prior art, office actions, and applicant’s responses, deletion and/ or amendments to claims, telephone and personal interviews, petitions and appeals, and other such events are carried out during an elaborate process, known as "patent prosecution. A successful patent prosecution leads to issuance of a patent, and may extent for a period of 2-3 years or beyond, and is carried out by the inventor or under his or her authority, by a patent attorney or a patent agent. There are strict requirements and statutory time limits for applicants’ responses, otherwise the application is deemed to be abandoned. There is a stringent duty of disclosure, termed as "Information Disclosure Statement," for disclosing to a patent examiner any known prior art material to the examination of the application. This duty extends to all connected with the patent prosecution of the application.
Patenting and maintaining a patent are fairly expensive. The patent office charges fees for most of the prosecution events. Patent Rules at 37 C.F.R. define approximately 125 fees for various activities during prosecution and post-prosecution; starting with the filing fee, $ 790, issue fee, $ 1370, and maintenance fees of $ 940, $ 2150, and $ 3320, due in the third, seventh and the eleventh years respectively. Several of these fees are considerably reduced in case of applicant being a "small entity." Non-payment of maintenance fees results in loss of patent rights.
Types of Patents:
USPTO has classified patents in three broad categories
Utility Patent covers the functional aspects of an invention, and its term is 20 years from the date the filing of the filing of the patent application, subject to payment of maintenance fees. Approximately 90 % of the patents issued by PTO are Utility patents.
Design patent covers ornamentality of an article of manufacture, and its term is 14 years from the date of patent grant. Design patent focuses on design and ornamentality as against the functionality stressed in case of Utility patent. No maintenance fee is required. 
Plant patent is issued for a new and distinct, invented or discovered asexually reproduced plant including cultivated sprout, mutant, hybrid, or newly found seedling, other than a tuber propagated plant or a plant found in an uncultivated state, and its term is 20 years from the date of patent application filing. No maintenance fee is applicable. 
Patent law under "35 U.S.C. § 112 "clearly defines the great extent to which an invention must be disclosed in a patent application:
"The specification shall contain a written description of the invention, and of the manner and process of making and using it in such full, clear, concise, and exact terms as to enable any person skilled in the art to which it pertains, or with which it is most nearly connected, to make and use the same, and shall set forth the best mode contemplated by the inventor of carrying out his invention.
The specification shall conclude with one or more claims, particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.- - - - - -(Emphasis added)
Claims define the metes and boundaries of an invention. These are like the legal description of real property, and are given "broadest reasonable interpretation and plain meaning" consistent with the specifications.  A well-drafted claim should distinguish itself from the prior art, should be broad enough to encompass foreseeable future technology, should be narrow enough to avoid reading on prior art, and must be written in clear and precise language.
No matter how elaborate the specifications of a patent are, or how precise and detailed the drawings are, it is only the claim or claims of a patent which can be infringed. Whether litigation focuses on patent infringement or validity, the core issue is often whether there is a narrow or broad interpretation of the patent claim.
Patent Infringement and litigation:
Infringement of a patent occurs by unauthorized making, using, offering for sale, selling or importing a patented invention. It may either be direct, or take a different flavor, such as inducement to infringement, or contributory infringement. The infringing device must have each or every element in the claim of the patent present (literal infringement), or its equivalent as defined under "The Doctrine of Equivalents". This doctrine is blessed by Supreme Court. "[O]ne who seeks to pirate an invention, like one who seeks to pirate a copyrighted book or play, must be expected to introduce minor alterations to conceal or shelter the piracy. Outright and forthright duplication is a dull and very rare form of infringement."  The Supreme Court also ruled: "[T]he substantial equivalent of a thing, in the sense of the patent law, is the same as the thing itself; so that if two devices do the same work in substantially the same way, and accomplish the same result, they are the same, even though they differ in name, form, or shape." 
As only a claim can be infringed, an elaborate analysis of the claim or claims is carried out. This analysis, also known as "claim construction", demands reading and interpreting the meaning of claim, and then contrasting the alleged infringing article against that claim. Two landmark court judgments teach a great deal on the topics of claim construction, and doctrine of equivalents:
In Markman v. Westview Insturments, Inc. , the jury found that Westview’s products had infringed Markman’s patent, however the trial court directed a verdict for Westview on its interpretation of the claim language. The Court of Appeals for the Federal Circuit (CAFC), as well as the Supreme Court subsequently affirmed this decision, an event that has dramatically transformed patent litigation, by redefining the role of juries, and by holding that "the construction of a patent, including terms of art within its claim, is the exclusive province of the court." The court further added that "the first issue of a simple patent case, consisting of a patent, is an issue for the court, whereas the second issue, determining whether infringement occurred, is an issue for the jury."
During a patent prosecution process, an applicant may delete a certain claim, or amend a claim to make it narrower to overcome rejection by the patent examiner. Under the Doctrine of Equivalents, the applicant, being bound by this prosecution history, is estopped from alleging that the infringed claim was intended to be broader (before it was amended), and is thus infringed by the infringing device. In other words, the applicant is prohibited from taking a stand other than what he or she took while prosecuting the patent application. In yet another landmark judgment in Festo Corp. v. Shoketsu Kinzoku Kogyo Dabushiki Co.,,  the Supreme Court disagreed with the CAFC decision on a "complete bar to the doctrine of equivalents, when prosecution history estoppel arises" and held: . . . "Prosecution history estoppel may apply to any claim amendment made to satisfy the Patent Act’s requirements, not just to amendments made to avoid the prior art, but estoppel need not bar suit against every equivalent to the amended claim element.
Defenses for infringer:
There are several defenses available to alleged infringers. Some common ones are: assertion of noninfringement, claiming that the patent is invalid, or claiming the invention does not meet the statutory subject matter requirement under § 101 or that it is not novel, useful, or unobvious. Fraud or inequitable conduct by a patentee can also invalidate a patent. An accuser may also assert patent abuse by price fixing, or tying arrangements, and delay in filing the claim for infringement by the patentee.
Patent law offers the strongest protection to intellectual property. Remedies may include preliminary and permanent injunctive relief, destruction of infringing inventory, collateral actions against competitors’ customers in the context of the infringing invention, compensatory damages, punitive damages, opening and auditing accounts of the infringer to access profit information, and attorney fees. Lack of intent is not a defense to a claim of infringement, although it is relevant to the issue of punitive damages.
Is it patentable? In most cases the answer could be yes, if it is new and non-obvious, and belongs to the category of "patentable subject matter" as defined by the laws. Patents have been issued for a pet diaper garment,  a single invention which is a combined grocer’s package which includes, grater, slicer, and mouse and fly trap,"  a scratching and petting device for household pets,  and several such devices. These may not be valuable, but there are thousands of patents that have changed the world for the better. How valuable such patents are, and what they contribute is defined by Dr. Land in these beautiful words: "The only thing that keeps us alive is our brilliance. The only thing that protects our brilliance is our patent." 
The complexity of patent law as summarized over one hundred years ago by Justice Brown: "The specification and claims of a patent, particularly if the invention be at all complicated, constitute one of the most difficult legal instruments to draw with accuracy,"  and is more valid today than in 1892 as today’s technological advances are really outpacing the Patent law, and are offering great challenges to attorneys to litigate, and to judges to interpret and redefine it.
1. Art. 1. § 8, Cl. 8
2. Tile 35, 35 U.S.C. § 101
3. State Street Bank & Trust Co. v. Signature Financial Group Inc. 47 USPQ2d 1596, 149 F3d 1368, (Fed. Cir. 1998)
4. Thomas Jefferson (Writing of Thomas Jefferson 75-76. Washington ed. 1871)
5. Diamond V. Chakrabarty, 447 U.S. 303, 309 (1980). Also refer "S. Rep. No. 1979, 82nd Con., 2d Sess.
6. Diamond v. Diehr, 450 US 175 (1981)
7. State Street Bank & Trust Co. v. Signature Financial Group Inc. 47 USPQ2d 1596, 149 F3d 1368, (Fed. Cir. 1998)
8. U.S. Patent No.5,960,411, granted to Peri Hartman, et al., Assignee: Amazon.com
9. U.S. Patent No. 5,794,207, granted to Jay Walker, et al., Assignee: Walker Asset Management, a holding company for Priceline.com
10. U.S. Patent No. 6,829,569 B1, issued to Drucker et al., Date of Issue Dec. 7, 2004
11. U.S. Patent No. 5,965,809, issued to Edward Pechter,, Date of Issue Oct.12, 1999
12. 35 U.S.C. § 171
13. 35 U.S.C. § 161
14. M.P.E.P. 2111 and 2111.01
15. Graver Tank & Mfg. Co. v. Linde Air Products Co., 339 U.S. 605, 85 U.S.P.Q. 328 (1950)
16. Machine Co. v. Murphy, 97 U.S. 120, 125 (1877)
17. Markman v. Westview Instruments, Inc. 116 S.Ct. 1384 (1996)
18. Festo Corp v. Shoketsu Kinzoku Kogyo Kabushiki Co., 535 U.S.722 (2002)
19. U.S. Patent No. 6,675,745 issued in January 2004
20. U.S. patent No. 586,025 issued in 1897
21. U.S. Patent No. 4,872,422 issued in October 1989
22. Dr. Edwin Land, 1967
23. Topliff v. Topliff, 145 U.S. 156, 171 (1892)
Amin S. Khan is a licensed patent agent and a paralegal. He teaches the Intellectual Property student of paralegal program at Elgin Community College. He also develops customized workshops, seminars and tutorials on Intellectual Property topics. He has a bachelor’s degree in Electrical Engineering.