How Is Patent Infringement Determined?

Owning a U.S. patent gives you important rights over your product, technology, or a big idea — we’ll call this your invention. Patent infringement occurs when some individual or entity infringes on your intellectual property rights over your invention. That is when someone enters the ‘prohibited territory’ defined by your patent.

How Is Patent Infringement Determined?

How patent infringement is determined can be a complicated process and can involve a lengthy legal proceeding. This article will provide an overview of patent infringement and the key elements in determining whether infringement has actually occurred. 

Patent Rights Generally

A U.S. patent gives patent holders the legal intellectual property right to exclude others from making, using, selling, or importing whatever is within the scope of the patent. The United States Patent and Trademark is the administering government body in the United States that grants patent approval for inventions.

Patent owners can be the sole legal source of the patent invention and use or sell the invention by themselves. Patent owners can also license the rights to the applicable patent to others. Finally, a patent owner can sell or transfer the applicable patent rights as a type of intellectual property asset. 

Patent Infringement Generally

In general terms, patent infringement is when someone carries out an act that infringes on a patent owner’s legal intellectual property right without the permission of the patent holder. An individual or entity will typically infringe the patent by making, using, selling, or importing whatever is within the scope of the patent without the patent owner’s direct permission to do so. The United States Patent Office does not determine or enforce infringement. Patent Infringement is determined and enforced by U.S. federal courts.

Types of Patent Infringement

There are two main types of patent infringement, with two subtypes of patent infringement. This provides a patent holder with numerous ways to bring a legal claim for patent infringement in federal or state court. 

The four types of patent infringement are:

1. Direct infringement;
2. Indirect infringement; 
3. Induced infringement; and
4. Contributory infringement. 

Direct Infringement

Direct infringement is defined by 35 U.S.C. § 271 of the U.S. patent law and essentially occurs when an individual or entity actively engages in a prohibited use of someone else’s patented property. 

Prohibited uses including making, selling, or importing to sell an invention within the United States. For example, if someone is developing and selling a computer product that is identical to yours, this would be direct patent infringement with an infringing product. 

Indirect Infringement 

Indirect infringement of a patent, on the other hand, is found when an individual or entity causes or assists another individual or entity is infringing on patented property. This indirect infringement must infringe on at least one material aspect of the patent claim. 

Within indirect infringement, there are two subtypes of indirect patent infringement: 

1. induced infringement; and 
2. contributory infringement. 

Induced Infringement

Inducing infringement occurs when an individual or entity actively induces another person or entity to make prohibited use of someone else’s patent. As an example, if an entity actively emails the ingredient list for a specific patented recipe to another entity, this would be induced infringement. 

Contributory Infringement

Contributory infringement occurs when a person or entity knowingly provides a product or component of a product or service that helps the recipient directly infringe on a patent.  Also, the provided product or component must not have a substantial non-infringing use. 

Basically, a person or entity must: 

1. Know of the patent; and
2. Know that his or her actions would lead to infringement of the patent.

A substantial non-infringing use of a patent is use that is not unusual, farfetched, illusory, occasional, or experimental.

Where to Bring a Patent Infringement Claim

Under United States law, patent holders can bring a patent infringement claim against alleged infringers for infringing use. Patent infringement actions arise under federal law, and thus the federal courts have exclusive jurisdiction.  But certain patent issues can be brought in state court. For example, a dispute regarding the ownership of a patent or over a licensing agreement arise under property law or contract law, which are both generally dictated by state law. 

It is a good idea to consult a patent attorney to understand your intellectual property rights for the applicable states as well as your rights under federal law to determine which venue is better suited for your specific infringement lawsuit. 

Elements of a Patent Infringement Claim

Under federal law, there are two main elements of a patent infringement claim: 

1. Ownership of a valid patent; and
2. Infringement of the patent by the defendant. 

These two main patent infringement elements have various components that make up the larger element, which we’ll explore below. 

Patent Ownership and Validity

Before you can proceed with the rest of your patent infringement claim, you must prove that you own a valid patent. This breaks down into two parts: ownership and validity. 

Patent ownership typically is proven based on written documentation of ownership assigning the patent to you. This often is the official documentation provided by the United States Patent and Trademark Office when it approves the patent. However, this documentation could also be a contract assigning to you the ownership rights of a patent. 

The validity of the patent must also be proven as an initial element of a patent infringement claim. An issued patent, however, is presumed valid – shifting the burden to the defendant to prove invalidity. Even if a patent has been issued for an invention, the validity of that patent can still be called into question. 

Courts can decide that a patent is invalid for a number of different reasons such as:

• Withheld information on a patent application;
• False information on a patent application;
• A claim within the patent is determined to be obvious;
• The description and/or the claims were unclear and ambiguous

Infringement of the Patent

To succeed on a patent infringement claim, a patent holder must next prove infringing use that infringes on the patent. Infringement can be broken down into three sub elements: 

1. the identity of the infringer;
2. the specific act of infringement; and 
3. the similarity to one or more patent claims.

Identity of the Infringer

A patent infringement action would typically name as a defendant every alleged patent infringer. This may be a particularly easy process if there is only one specific individual who has infringed on your patent. It can become much more complicated, however, when there are multiple individuals and businesses involved. 

It could be that multiple organizations were involved with building and selling the infringing invention in a collaborative process. If this is the case, then each and every organization needs to be named in your patent infringement complaint.

Don’t worry if you don’t know the names and identities of each and every infringing individual or entity before you bring your patent infringement lawsuit. You will have the opportunity to amend your complaint several times in the litigation process to name additional parties as you learn more information. 

The formal process of discovery will likely provide you with key evidence from the other side that will help you to identify these additional parties. Moreover, the defendant is often required by the court processes to identify other parties who are potentially relevant to your claim. 

Specific Act of Infringement

A patent holder bringing a patent infringement lawsuit will need to identify a specific act of infringement carried out by the infringing party. As addressed above, patent infringement is the making, using, selling, or offering to sell a patented invention. This is what will need to be proven. Typically, one or more distinct act by the alleged infringer must be established to meet this requirement. 

The best evidence for proving infringement will be the physical evidence of the competing invention. In this way, the accused product can be compared side to side to the patented invention. If you have an indirect infringement claim, then you will ideally have some documentary evidence of directing or assisting in the infringement, perhaps in emails or letters.  

Similarity to One or More Patent Claims

Finally, this sub element addresses the specific claims that make up the patent. To prove patent infringement, a patent holder must demonstrate infringement of a specific patent claim by the accused product. Patents are made up of at least one, but often various “claims” that together make up the patented invention.  

The infringing product must infringe on at least one of these claims as listed in the patent approved by the Patent Office. How claims are constructed by the court is explained in further detail below. 

Claims Construction Generally

As noted above, one key element in proving patent infringement is proving that a specific patent claim listed in the validly issued patent has been infringed on by the infringing product at issue. To infringe a claim, the alleged infringer must meet each and every element in it.

Claims construction is the process by which a court or other tribunal determines the scope and meaning of a patent’s claims. It is only by properly interpreting and defining the scope and meaning of a patent claim can a fact finder then determine whether a patent has been infringed. 

Therefore, this is done before a fact finder determines whether the accused product is in fact an infringing product. 

Significant financial and time resources are often spent on the claims construction process and analysis. This is because patent infringement claims very often hinge on the interpretation of a patent claim’s scope. 

This means both sides of a patent infringement lawsuit will spend considerable time and resources in preparing for the court’s claim construction interpretation. The claims construction dispute often makes or breaks a patent infringement claim.

Because patent infringement and validity depend on the determination of the proper patent claim scope, both patent owners and alleged infringers typically expend significant resources addressing claim construction. 

In most patent infringement lawsuits, the parties focus on one or more claim terms and assign different meanings to the terms to support their respective positions. Typically the parties have significant disputes concerning the appropriate claim construction because often the claim construction ruling will eliminate the relevance of a claim, in which case no infringement would have occurred. 

Who Construes Claims Construction

The claims construction analysis for patent infringement lawsuits is considered a legal issue as opposed to a factual issue. In fact, the United States Supreme Court specifically decided in Markman v. Westview Instruments Inc., 517 U.S. 370 (1996), that claim construction is a question of law reserved for the court and not a question of fact left to the fact finder. What this means is that the construction of a patent’s claims is determined by a court, not by a fact finder (e.g., by a jury at trial). 

Typically claims constructions are carried out by a federal court, as most patent lawsuits are brought in federal court. However, claims construction is also completed by the International Trade Commission (ITC) in specialized and specifically applicable proceedings regarding the importation of allegedly infringing goods. 

When Claims Construction Takes Place

Because a court conducts claims construction rather than a fact finder, the claims construction analysis can be done before trial at summary judgment if not earlier in the legal proceeding. In fact, a court must construct the patent claims before a fact finder can evaluate those construed claims against the allegedly infringing invention.

Therefore, claims construction is typically done under a separate hearing that is referred to as a “Markman hearing.” This hearing is named after the landmark Supreme Court case noted above.  

These Markman hearings are pre-trial hearings held in federal district court in which the court examines evidence from all parties in the case about the appropriate meanings of the relevant keywords that are used in a patent claim. 

Evidence Review at Claims Construction Hearings 

The Federal Circuit has established specific requirements for these claims construction hearings, or Markman hearings, and the type of evidence that can and should be reviewed at the hearing. 

The Federal Circuit is the appeals court that handles all appeals related to specific areas of federal law, including patents. In the court system, they are one level below the Supreme Court and can set the standards that must be applied to patent law claims in all federal district courts within every state. 

In the Federal Circuit court case Phillips v. AWH Corp., the Federal Circuit concluded that proper claim construction requires a review of the patent’s intrinsic evidence and — only when appropriate — a review of the extrinsic evidence related to the patent. 

Why Evidence Is Reviewed

Intrinsic evidence, and sometimes extrinsic evidence, is reviewed for a few reasons. 

Intrinsic evidence helps the court give the specific patent claim the meaning that it would have to a person of ordinary skill in the applicable field at the time the invention was established.  This person of ordinary skill in the applicable field is a standard used by the court system. 

The person of ordinary skill can be defined as a fictional, objective person who has the average knowledge, skill and expertise in the specific technical or scientific field of the claimed invention.

In addition, a review of intrinsic evidence helps courts to interpret the claims to cover what was actually invented by the patent holder and what the patent holder actually intended the patent to cover. 

Finally, intrinsic evidence is reviewed by courts to help preserve a patent claim’s validity except where that would conflict with the claim’s language and corresponding specification. This is because, in federal court, patents are presumed valid. 

Intrinsic Evidence

The Federal Circuit has determined in case law that intrinsic evidence is the first place that a court should look to when conducting its claim analysis. If a court can analyze the claim based on the intrinsic evidence, then the court should stop its inquiry and should not review any outside, extrinsic evidence. 

There are three types of intrinsic evidence used by the courts in evaluating claims construction:

• The patent’s claims; 
• The patent’s specification; 
• The patent’s prosecution history. 

Intrinsic evidence is also referred to as the “public record” of the patent. These three elements make up the public record of a patent because these are all available to the public via patent searching within the United States Patent and Trademark Office database.

Patent Claims

Patent claims define the scope and boundaries of the patented invention. One way to think of patent claims is as a legal description of a specific plot of land that will explain and help determine the scope of which land ownership. In other words, the general purpose of patent claims is to state the legal boundaries of a patent. 

Interestingly, the purpose of a patent claim is not necessary to explain an applicable technology or how a specific product operates but to state the legal boundaries of the patent grant. Patent claims must distill the necessary and specific and also distinguish itself from the prior art that is applicable. 

Context is key in interpreting patent claims. Terms within patent claims are generally given their ordinary and customary meaning as understood by a “person of ordinary skill” in the applicable field. Terms used in patent claims are interpreted according to the context in which the specific term appears in the claim. 

So, if a patent applicant uses different terms to address and establish similar claim explanations or limitations, then these terms will be interpreted to have different meanings. This means some terms within a claim may have a different meaning than the term’s ordinary and customary meaning. 

Claims are also considered based on the place within the patent claim that the term appears. There are three parts of a patent claim:

1. Preamble:
   1. This is the initial section of a patent claim that identifies the type of invention the claim relates to and any potential limits on the claim in particular circumstances.
2. Transitional Phrase:
   1. This is a transitional phrase placed after the preamble that either limits or does not limit the claim to the specific limitations that are thereafter listed within the claim.
      1. “Comprising” is the typical phrase used to not limit the claim to the limitations that may follow. 
      2. “Consisting of” is the typical phrase used to limit the claim to the limitations that may follow. 
3. Body:
   1. There are one or more limitations listed in the body of the claim. 
   2. Limitations are selected elements or steps implementing an invention.

Based on the applicable case law, courts typically attach different meanings and scopes to the different words or phrases that are used in separate claims within the same patent. This doctrine to apply different meanings and scopes to different words or phrases is only a legal presumption. 

Therefore, this presumption that different terms have different meanings can be overcome by the contents of the patent claim’s specification and prosecution history. 

Specifications

Specifications, in turn, teach about the underlying claims within the patent. The specification’s description can act as a dictionary for the patent claims in that it can help to explain in more of a narrative fashion the underlying invention. The specification can also more robustly explain and define terms as they are used in the claims. 

Because of their role in teaching about the underlying patent, specifications can be especially pertinent and important in a court’s claim construction analysis. In fact, when a proposed construction of a claim most naturally aligns with the description of the invention in the specification, it will typically be dispositive in constructing that claim. 

Specifications can be dispositive when they describe an invention’s preferred or sole invention embodiment or if specifically excludes an invention’s embodiment. Specifications also shed light on claim constructions where they distinguish prior art and explain how the patent differs from applicable prior art.   

However, specifications also should not be used to take claims constructions to their extreme. The specific language of the claims is still highly relevant and important in the claims construction analysis. There can be a fine line between reading a claim as more fully explained by the patent’s specification, and reading a limitation into the claim from the patent’s specification.

It is important to note that a patent owner can define specific terms within the patent’s claims. These definitions can differ from the ordinary meaning typically given to that specific term. If a patent drafter chooses to define terms within the patent, the definitions are often set out in the specification. 

Overall, courts look to a patent’s specification to determine the meaning of a term within a claim as it is used by the inventor within the context of the invention in its entirety. 

Prosecution History

The third element of a patent’s intrinsic evidence is the patent’s prosecution history. The prosecution history of a patent is simply the entire history from the time a patent application was submitted to the United States Patent and Trademark Office to when patent approval is granted. Patent applications are assigned to a specific patent examiner within the Patent Office.

This patent examiner conducts a comprehensive review of the patent and its claims, and reviews related prior art at length. Patent examiners issue Office Actions, which are communications to the patent applicant setting forth various questions or statements that a patent applicant can then submit responses to. 

This prosecution history can often show significant back and forth communications between the patent examiner and the patent applicant. This paper trail often provides helpful information that sheds light on the proper interpretation of a claim’s overall scope. 

For example, if a patent examiner asks whether a specific mechanism is contained within the scope of a specific patent claim, and the patent applicant writes a response letter indicating the mechanism is not included in the patent claim, this interpretation will be helpful in later interpretation of whether or not a claim encompasses that mechanism. 

Notably, of course, the disclaimer language of a subject matter or interpretation must be clear and unambiguous within the prosecution history for the history interpretation to control. 

Prosecution history will vary in its helpfulness depending on how much discussion occurred between the patent applicant and the patent examiner. When a patent is quickly approved, there will be less of a prosecution record, and thus would be less helpful. In general, prosecution history is often less helpful than other elements of intrinsic evidence, especially the specification. 

This is because prosecution history is not always clear and is often a reflection of the negotiation that occurs between a patent examiner and a patent applicant. 

Extrinsic Evidence

Extrinsic evidence in claim construction analysis is relevant information outside of the intrinsic evidence that assists in analyzing a patent claim. Extrinsic evidence is only used if the meaning of a claim and its applicable limitations are not apparent from the intrinsic evidence. 

If this is the case, then a court looks to extrinsic evidence to try and resolve any lack of clarity in a claim and its corresponding terms.

Case law suggests that relying on extrinsic evidence should only be used in rare instances.  In general, extrinsic evidence should only be used in very rare circumstances to aid the court in interpreting patent claims when it cannot do so otherwise. 

So, for example, if intrinsic evidence considered as a whole does not allow a court to fully interpret a term of art used in a patent claim, then extrinsic evidence may be used to shed light on that specific term. 

Extrinsic evidence is typically evidence such as:

• Expert testimony; 
• Pertinent treatises;
• Applicable journals;
• Dictionary definitions.

Treatises and dictionaries are given greater weight by the court than other extrinsic evidence. This is because expert testimony can be more easily tailored to align with the plaintiff or defendant’s side of the argument. 

Expert testimony can also be used in particular circumstances. Typically, expert testimony is used to:

• Explain how an invention works; 
• Establish a specific term within the patent; 
• Provide background explanations of the applicable technology; or
• Align an interpretation of a patent’s technical components with the ordinary meaning of a term used by a person of ordinary skill in the applicable field. 

Courts use extrinsic evidence to understand:

• Underlying meaning of technical terms; 
• Relevant scientific principles and applications; 
• Current advancements and environment in the applicable field. 

Claims Construction Hearings

Because a court’s construction of a claim is so important to the outcome of a patent infringement lawsuit, claim construction hearings are a very important part of a patent infringement claim. As noted above, a court construes patent claims in a specific hearing called a Markman hearing.

A court will often establish the date for a Markman hearing during what is called a Rule 16 conference. A Rule 16 conference is typically held once both sides have filed their complaints and corresponding answer or another responsive pleading. At a Rule 16 conference, a court will require that the parties identify:

• the pertinent claim terms that will need construction;
• The proposed initial construction of applicable terms; and
• The areas of the alleged infringement.

Markman hearings can be conducted at any point during the litigation process, as there is no specific rule setting a time limit within the litigation that a Markman hearing needs to take place. That means a Markman hearing can be conducted before, during, or after discovery has closed. It can even take place during a trial. Typically, however, a Markman hearing will take place before trial. 

Markman hearings are often set apart in two parts. First, a Markman hearing acts as a tutorial to instruct the judge on the underlying scientific background of the patent and its corresponding claims. Each court will have different requirements for a Markman hearing. Some courts want a joint tutorial while others allow for each side to present their own tutorial. 

Markman hearings also consist of oral testimony and argument. This often includes live testimony of witnesses, often expert witnesses, on the witness stand. 

It is important to properly prepare for a Markman hearing.  You should become well acquainted with the intrinsic evidence of your underlying patent. Moreover, you must be able to present complex scientific information to the court so that the court understands the applicable scientific area applicable to your patent. 

These presentations at a Markman hearing are often presentations that explain the applicable scientific issues at hand in a manner and means that is understandable. Parties also often used physical presentation boards to convey information to the court. 

Fact Finder Determines Infringement

After a court has constructed the applicable claims in a patent infringement lawsuit, the fact finder must then determine whether or not the accused product is in fact an infringing product based on the applicable patent claims. This is typically done in the context of a jury trial. 

Expert testimony is typically presented on both sides to discuss the competing inventions and present arguments as to why the accused product infringes or does not infringe on the applicable patent. 

Documentary evidence, typically in the forms of diagrams, charts, journals, emails, and the like, to further demonstrate similarities and differences between the accused product and the patented one. 

Ultimately, after the evidence is presented, the factfinder will make a determination about whether or not the competing invention has infringed on the patented invention. 

Defenses to Patent Infringement

As part of the process of presenting information to the fact finder on infringement, the defendant will often put on a defense to argue that its invention is not in fact infringing on the applicable patent. There are multiple patent infringement defenses, including:

• There is no actual infringement;
• The applicable patent is invalid;
• The applicable patent is unenforceable.

Fact finders, i.e., a jury, must find that a patent claim has been infringed. Therefore, in interpreting whether there has been infringement, the facts must be construed to establish if the patent claims have been infringed by the accused product. 

Doctrine of Equivalents

The doctrine of equivalents is a legal doctrine that can come into play in patent infringement lawsuits.  The doctrine of equivalents allows for a finding of patent infringement for a patented invention even if an infringing invention does not fall within the literal scope of the infringed invention, but is nevertheless equivalent to the infringed invention. 

To use the doctrine of equivalents, the competing invention must:

1. Perform substantially the same function as the infringed invention;
2. In substantially the same manner; 
3. To achieve the same result. 

The doctrine of equivalents also can apply when specific elements of the accused product or invention are interchangeable with the patented one, and a person with ordinary skill in the applicable field would have known that these elements were interchangeable when then infringement occurred. 

Limitation of the Doctrine Of Equivalents

There are limitations to the legal doctrine of equivalents. This doctrine must be applied to the individual elements of a patent claim rather than to the patent as a whole. Therefore, the doctrine does not come into play until after the claims construction analysis has occurred.

The patent holder must prove that the infringing claim was not foreseeable to someone of ordinary skill in the same field.  This foreseeability element is interpreted broadly by the court.  Courts have found that an equivalent is foreseeable if someone in the field would have known the equivalent existed, even if the suitability of that equivalent as an alternative was unknown. 

There is another limitation to the doctrine of equivalents. If a patent discloses an alternative way to create the invention but does not specifically claim this way within the patent claim, then this alternative way is not covered by the patent’s protection. 

This alternative way can therefore be used freely by the public. This is why it can be very important not only to draft a patent application that explains your product or invention in detail but to also make sure to make as many claims as possible related to your invention. 

Damages Awarded in a Patent Infringement Lawsuit

If a patent infringement lawsuit is successful, patent holders typically receive an award of damages from the infringer for the infringement on the patented invention.  This damage award can be determined either by the fact finder at trial, or by the court following a trial. 

Section 284 of the Federal Patent Act provides the underlying key framework for a damages award in a patent infringement lawsuit. Damages must be the amount that will compensate the patent holder for the infringement and at least must amount to a reasonable royalty for the infringer’s use of the patented invention. 

The court also can award up to three times the actual amount of damages incurred, if the judge feels that the situation warrants it. This is typically only done in egregious instances of patent infringement. 

Usually, damages are awarded in the form of royalty payment for infringing on the patented invention. This means the infringing party would still be able to market the competing invention but would have to pay the patent holder a percentage of any profit that it makes. 

A patent holder is also eligible to recover what are called “lost profits.” Lost profits are the profits that a patent holder lost because of the infringing product. Lost profits are not often awarded as they can be more difficult to prove because they are often viewed as speculative by the court. 

Another potential remedy for patent infringement is to obtain an injunction against the infringing product.  This would prevent the infringing party from continuing to make and sell the infringing invention. An injunction is typically seen as a more extreme remedy by the court. Therefore, a court usually avoids awarding an injunction except in more unique circumstances where it may be justified. 

Drafting Patents to Ensure Claim Construction Analysis

Because patent infringement can become an issue down the line for your patent, it is helpful to draft your patent application with patent infringement lawsuits in mind. Specifically, it is important to draft your patent claims with the thought in mind that a court may one day analyze each specific word used in the claim drafting.

Thoroughly Search for Prior Art

Make sure that you thoroughly research all the potential prior art that is available. More than that, make sure that your claims and specification are drafted in a way that distinguishes any prior art that may be similar to your claim. It is important to find the line between specificity and generality. You want to distinguish the prior art enough that you are awarded the patent because your invention is sufficiently different. On the other hand, you do not want to draft yourself into a corner that a court may then hold you to later when you are in a patent infringement lawsuit. 

Construct Well Written Claims

A well written claim is very important to succeeding in a patent infringement lawsuit. Consult a patent attorney about how many claims are best for your particular invention. A patent will have a range of claim numbers. In fact, you only need one claim for a patent. 

Typically, though, a patent application will have around 20 claims. This is because this is the most claims that can be made in a patent application without paying additional filing fees.

Make sure to use terms in a clear manner within each and every claim. Make sure you use these terms consistently throughout the claims and the specification. Place details in the specification that will help shed light on any potential areas of confusion within the claim language. 

Try to anticipate the areas where an outside individual will have questions or find something unclear or incomplete. This will save you money down the line, as a patent examiner will likely be the first to ask those questions. 

An experienced patent attorney will be able to help point out the areas of weakness in how your claims are drafted. Your attorney will also be able to suggest where and when to define terms, and when to allow terms to be left undefined because they are intuitive for the reader.