Patent Law: Patent Types, Filing Requirements, and Infringement Claims

Patent law protects specific inventions, including processes, machines, articles of manufacture, and compositions of matter.

These four categories come from 35 U.S.C. § 101. Patent law does not protect ideas, discoveries of natural laws, or abstract concepts by themselves. An inventor must present a concrete, described invention rather than a general concept or wish.

Some innovations are better kept confidential than patented, because a patent requires public disclosure. Businesses that want to guard a process without revealing it often rely on industrial technology protection and trade secret measures instead. The choice between patenting and secrecy depends on how easily the invention can be reverse engineered and how long it holds commercial value.

There are three types of patents: utility, design, and plant patents.

Utility patents cover how an invention functions, such as a new device, method, or chemical composition, and they make up the large majority of patents granted. Design patents cover the ornamental appearance of a functional article, not the way it works.

Plant patents cover new and distinct plant varieties that are asexually reproduced.

Each type has its own term and filing requirements, which affects how inventors decide to protect a product. In some cases, a single product can be covered by more than one type, for example a device protected by a utility patent and a design patent at the same time.

The requirements for a patent are patentable subject matter, utility, novelty, nonobviousness, and adequate disclosure.

Under 35 U.S.C. § 101, the invention must fall within an eligible category and be useful. Under § 102, it must be new, meaning it was not already disclosed to the public before the relevant filing date. Under § 103, it must not be an obvious variation of existing technology to a person of ordinary skill in the field. Under § 112, the application must include a written description, enable others to make and use the invention, and define the claims with enough clarity to set the boundaries of protection.

Abstract ideas, laws of nature, and natural phenomena cannot be patented.

Courts apply the Mayo and Alice eligibility framework to decide whether a claim is directed to one of these ineligible concepts and, if it is, whether the claim adds an inventive concept that makes it patent eligible. The Supreme Court set out this two-step approach in Mayo Collaborative Services v. Prometheus Laboratories (2012) and Alice Corp. .. CLS Bank International (2014).

Mathematical formulas, purely mental steps, and general business methods often fail this test. The boundary is heavily litigated in software, financial technology, and medical diagnostics, where claims can be close to abstract ideas. Careful claim drafting, as seen in fields like nutraceutical patents, can determine whether a claim survives an eligibility challenge.

You apply for a patent by filing either a provisional or a nonprovisional application with the USPTO.

A provisional application establishes an early filing date and gives the inventor 12 months to file a full nonprovisional application, a period that cannot be extended. A provisional application is not examined and does not itself become an issued patent. It only preserves an early filing date if a proper nonprovisional application follows within the deadline.

The nonprovisional application is examined for compliance with the statutory requirements, and the examiner may issue rejections called office actions that the applicant must answer. Public disclosure or sale of an invention can start a one-year clock to file in the United States and can bar patent rights in many other countries that require absolute novelty. Inventors in regulated fields such as pharmaceutical R&D should track these dates before publishing, presenting, or selling.

Utility and plant patents generally last 20 years from the relevant filing date, while design patents filed on or after May 13, 2015 generally last 15 years from grant.

Utility patents require periodic maintenance fees to stay in force. Those fees are due at 3.5, 7.5, and 11.5 years after the patent is granted, and missing them can cause the patent to lapse. Design patents do not require maintenance fees.

Patent term can be adjusted in limited situations, such as delays caused by the USPTO during examination. Once a patent expires or lapses, the invention enters the public domain and anyone may use it. Tracking these dates is part of managing a patent as a business asset.

Patent infringement is the unauthorized making, using, selling, offering for sale, or importing of a patented invention.

Patent disputes may involve direct infringement, induced infringement, contributory infringement, literal infringement, or infringement under the doctrine of equivalents, which reaches products that are not identical but equivalent in how they work. A court may award damages adequate to compensate the patent owner, but no less than a reasonable royalty, under 35 U.S.C. § 284. Damages can be increased up to three times for willful infringement, and courts may award attorney fees in exceptional cases under § 285.

Under 35 U.S.C. § 286, a patent owner cannot recover damages for infringement that occurred more than six years before the complaint was filed. Related rights, such as brand protection under trademark law and licensing arranged through international contracts, often arise alongside patent claims in the same commercial dispute.

Yes, an accused infringer can challenge the validity of the patent as a defense or through a separate USPTO proceeding.

In litigation, a defendant may argue that the patent is invalid because it fails novelty, nonobviousness, or the disclosure requirements. Separately, accused infringers may challenge patent validity through USPTO proceedings such as inter partes review before the Patent Trial and Appeal Board. Post-grant review is another option available within a limited window after a patent is granted.

These proceedings can run in parallel with a court case and sometimes pause it. Because both infringement and validity carry technical and procedural complexity, and because the six-year damages limit applies, parties on either side should consult a registered patent attorney early.

Patent law is the federal law that grants inventors exclusive rights to their inventions for a limited time. It is based in Article I of the Constitution and set out in Title 35 of the U.S. Code. It defines what can be patented, how patents are obtained through the USPTO, and how they are enforced.

The three types of patents are utility, design, and plant patents. Utility patents cover how an invention works. Design patents cover the ornamental appearance of an article. Plant patents cover new, asexually reproduced plant varieties. Utility patents are by far the most common type filed and granted.

Utility and plant patents generally last 20 years from the relevant filing date, provided maintenance fees are paid on utility patents. Design patents filed on or after May 13, 2015 last 15 years from grant. When a patent expires, the invention enters the public domain and can be used freely.

An invention is patentable if it is eligible subject matter, useful, novel, nonobvious, and adequately described. These requirements come from 35 U.S.C. .ections 101, 102, 103, and 112. Abstract ideas, natural laws, and natural phenomena cannot be patented, even when the other requirements are satisfied.

A provisional application preserves an early filing date and is not examined, and it lasts 12 months without extension. A nonprovisional application is the formal application that the USPTO examines and that can mature into an issued patent. A provisional only helps if a nonprovisional is filed within the 12-month window.

Patent infringement is making, using, selling, offering to sell, or importing a patented invention without the owner's permission. It is defined in 35 U.S.C. § 271 and may be direct or indirect. A patent owner can seek an injunction and damages, and damages may be tripled when the infringement is found to be willful.

Yes, a granted patent can be challenged. An accused infringer can raise invalidity as a defense in court, and third parties can challenge validity at the USPTO through inter partes review before the Patent Trial and Appeal Board, or through post-grant review within a limited period after grant. These challenges test novelty, obviousness, and disclosure.

You are not legally required to hire a patent attorney, but the process is technical. Only practitioners registered with the USPTO may represent applicants. Because claim drafting, prior art searches, and examiner responses require legal and technical skill, and deadlines are strict, many inventors work with a registered patent attorney or agent.