A patent grants its owner the exclusive right to use, make, sell, and license the patented invention for a maximum period of twenty years from the patent's filing date. Patent infringement occurs when someone uses, makes, sells, or distributes a patented invention without the permission of the patent owner during that term. The scope of what is protected — and therefore what constitutes infringement — is defined precisely by the patent's claims, which are the legally operative language in the patent document. This means that understanding both the boundaries of your own patent and the activities of an alleged infringer requires careful claim analysis, which is why experienced patent counsel is essential to any infringement assessment. TCP Law assists both patent owners enforcing their rights and parties that have received infringement claims, and offers a free consultation to help you evaluate your situation.

Patent infringement can take several distinct forms. Literal infringement occurs when all elements of a patent claim are precisely replicated in the infringing product or process — the closest and most straightforward form of infringement. Infringement under the doctrine of equivalents occurs when the infringing product or process does not literally replicate the patent claims but performs a substantially similar function in a similar way to achieve similar results. Beyond these two frameworks, infringement is also categorized by the infringer's role: direct infringement occurs when a person or entity directly makes, uses, sells, or offers to sell a patented invention without authorization; contributory infringement occurs when a party supplies or imports a component specially made or adapted to infringe a patented invention; and induced infringement occurs when a third party actively encourages or assists another party to infringe a patent, such as by providing instructions or equipment that enable infringement.

Literal infringement is the most direct form — it occurs when every single element of a patent claim is precisely replicated in the accused product or process. If even one claim element is missing from the accused product, there is no literal infringement. The doctrine of equivalents fills this gap by extending infringement liability to products or processes that do not literally copy the claims but nevertheless perform a substantially similar function in a substantially similar way to achieve substantially similar results. This doctrine exists to prevent competitors from making minor, insubstantial changes to a patented invention to avoid literal infringement while still appropriating the core of what the patent protects. Both theories of infringement are evaluated on a claim-by-claim, element-by-element basis, making detailed claim analysis central to any infringement determination.

Yes — you do not need to be the party that directly makes or sells a patented invention to face patent infringement liability. Contributory infringement occurs when a person or entity supplies or imports a component that is specially made or specially adapted for use in infringing a patented invention. The key is that the component itself must be specifically designed or adapted for the infringing use — supplying a generic, multi-use component that happens to be used in an infringing product does not typically constitute contributory infringement. Similarly, induced infringement — actively encouraging or assisting another party to infringe a patent through instructions, equipment, or other means — also carries liability even without directly making the patented product. Both theories extend patent enforcement beyond the most obvious infringer to others in the supply or distribution chain who knowingly facilitate the infringement.

Patent infringement remedies fall into three primary categories. Monetary damages compensate the patent holder and may cover lost profits — the revenue the owner would have made but for the infringement — or, at minimum, unpaid royalties representing what the infringer would have paid had they obtained a license. A temporary injunction is a court order that stops the alleged infringer from continuing the infringing activity while the case is being decided; to obtain one, the patent owner must demonstrate irreparable harm, that monetary damages would be insufficient compensation, that granting the injunction would balance the hardships appropriately, and that it would not harm the public interest. Legal costs, including attorney fees, may also be awarded by the court if it finds the infringement was willful. Together, these remedies are designed both to compensate the patent owner and to deter future infringement by others.

The Patent Trial and Appeal Board (PTAB) provides an alternative to federal court for third parties to challenge the validity of an issued patent. Post-grant proceedings before the PTAB are generally faster and less expensive than federal litigation, and they offer several distinct mechanisms depending on the grounds and timing of the challenge. Post-grant review (PGR) must be filed within nine months of a patent's issuance and can challenge validity based on prior art, lack of novelty, obviousness, or insufficient disclosure — it is granted if at least one challenged claim is shown to be more likely than not unpatentable. Inter partes review (IPR) is filed after the nine-month PGR window and challenges validity based solely on patents and printed publications — it is granted if there is a reasonable likelihood that at least one challenged claim will be found unpatentable. Ex parte reexamination can be filed by the patent owner or a third party at any time and is limited to challenges based on other patents and printed publications. A derivative proceeding addresses a different scenario entirely: it may be initiated by a person who believes the named inventor derived the invention from them and filed before them.

An inter partes review (IPR) is a PTAB proceeding that allows a third party to challenge the validity of an issued patent based solely on prior art in the form of patents and printed publications. An IPR petition may be filed starting nine months after a patent's issuance — after the post-grant review window has closed — and the PTAB will institute the proceeding if there is a reasonable likelihood that the petitioner will prevail on at least one challenged claim. IPR is commonly used by companies that have received a patent infringement claim and want to challenge the validity of the asserted patent through a faster, less costly administrative process rather than raising invalidity as a defense in federal court. Because IPR is limited to patent and printed publication prior art, having a thorough prior art search completed before filing is essential to building a strong petition.

Ex parte reexamination is a USPTO proceeding in which a patent's validity is challenged based on prior art in the form of other patents and printed publications, and it can be initiated by either the patent owner or a third party at any time during the patent's term. Unlike inter partes review, ex parte reexamination is largely conducted between the patent owner and the USPTO examiner — the third-party requester has limited involvement after the proceeding is initiated. If the USPTO finds a substantial new question of patentability, the patent owner has the opportunity to modify or cancel the contested claims to overcome the identified issues, provided the modifications do not increase the scope of the patent. This mechanism can be valuable for patent owners who discover problematic prior art they want to proactively address, as well as for third parties who want to raise validity questions without the full evidentiary demands of an inter partes review.

Receiving a patent infringement claim — whether through a cease-and-desist letter or a federal lawsuit — requires a prompt and informed response. The first step is to have a qualified patent attorney analyze the asserted patent's claims against your product or process to determine whether infringement actually exists, either literally or under the doctrine of equivalents. There may be strong defenses available, including that your product does not actually meet every element of the asserted claims, that the patent is invalid in light of prior art, or that the patent is unenforceable. Depending on the strength of the claim and your business circumstances, options may include negotiating a license, challenging the patent's validity through PTAB proceedings, designing around the patent, or defending in federal court. TCP Law assists clients in evaluating and responding to patent infringement claims and offers a free consultation to help you understand your exposure and options.

Yes — and this misconception leads many businesses directly into infringement liability. The doctrine of equivalents exists precisely to address this scenario: an accused product or process that does not literally replicate all elements of a patent claim can still infringe if it performs a substantially similar function in a substantially similar way to achieve substantially similar results. Minor modifications that do not fundamentally change how the invention works are unlikely to avoid infringement under this doctrine. Additionally, even a component-level supplier who provides parts specially made or adapted for an infringing product can face contributory infringement liability, and a party who provides instructions or equipment that enable someone else to infringe can face induced infringement liability — neither requires directly copying the patented invention. Whether a proposed modification is sufficient to avoid infringement requires a careful claim-by-claim analysis by a qualified patent attorney, not a judgment call made in isolation.