Patent Infringement

Terms:

Patent Infringement:
Using or manufacturing a patented product without the owner’s permission (by license, waiver, or other contract) can constitute infringement and expose the unauthorized user/manufacturer to liability, even if the infringement was unintentional.

Direct Infringement:
Actively engaging in a prohibited use of someone else’s patented property.

Induced Infringement:
Actively inducing someone to make prohibited use of someone else’s patented property.

Contributory Infringement:
Contributing to the unauthorized use of someone else’s patented property can also constitute infringement under patent law.

Question of Law:
A question of law is something which is answered by the judge, not by the jury. While the judge may need to rely on various facts in making her decision, the decision is ultimately hers.

Question of Fact:
A question of fact is one which is answered by the finder of fact in a case. In a jury trial, it is the jury’s job to make these determinations. When there is no jury, however, the judge will act as the finder of fact.

Doctrine of Equivalents:
The doctrine of equivalents is a legal rule in most of the world's patent systems that allows a court to hold a party liable for patent infringement even though the infringing device or process does not fall within the literal scope of a patent claim, but nevertheless is equivalent to the claimed invention.


As with copyrights and trademarks, unauthorized users of protected intellectual property can be held accountable under patent law. This is at the heart of patent protection. Infringement of patents, however, is a somewhat more complex issue than it is in other areas of intellectual property law.

Chapter 28 (§§271, 272 and 273) of Title 35 is most relevant here. There are so many important cases touching on §271 that the LEXIS entry for this section is split into two parts. This should serve as some warning, therefore, as to the wealth of material which cannot be covered within the scope of this course.

Direct Infringement v. Induced Infringement & Contributory Infringement

§271(a) addresses what is known as direct infringement. This is analogous to protections against infringement which exist in copyright and trademark law. With patents, however, a party who does not herself use or manufacture a protected invention can still be held liable for infringement under §271(b) or §271(c) under the theories of induced infringement and contributory infringement.

Some use the term “indirect infringement” to refer to both subsection (b) and (c) cases, while others reserve this term exclusively for induced infringement. Therefore, in the name of simplicity we will avoid the term “indirect infringement” altogether. Be aware, however, that the term is used extensively by courts and scholarly texts. That said, most seem to consider both induced infringement and contributory infringement as forms of indirect infringement.

The provisions for infringement under subsections (b) and (c) are dramatically different from anything we’ve seen in copyrights and trademarks:

Example 1: Matthew and Meagan are siblings who are fiercely competitive with each other. One day Matthew challenges Meagan to make a reproduction of the patented “Fuzzinator” and sell it to their friend, Toby. Not wanting to lose face, Meagan produces an infringing copy of the machine and successfully sells it to Toby. While Meagan is liable under §271(a) for patent infringement, Matthew is liable under §271(b) for actively inducing the infringement.

Example 2: A few days earlier, Matthew had challenged Meagan to duplicate a drawing from their favorite book, “Doug the Dog  Deserves Dessert.” The infringing copy she produces in no way exposes Matthew to copyright infringement liability.

§271(b) induced infringement requires more than merely suggesting that someone could benefit from a patented product. The subsection establishes liability for someone who “actively induces infringement,” which requires some sort of purposeful or intentional act. Demonstrating to others how a device can be used to recreate a patented device is enough. See e.g. Fromberg, Inc. v. Thornhill, 315 F. 2d 407 (CA5 Tex 1963). The plaintiff claiming infringement must show that the defendant knew or should have known that her actions would induce others to infringe on plaintiff’s patent. See Hilgraeve, Inc. v. Symantec Corp. 272 F. Supp 2d 613 (E.D. Mich. 2003).

Example: Meagan is not particularly bright (which is why Matthew is able to convince her to do so many silly things). She is, however, quite enamored of her older brother and tries to emulate him in any way possible. She therefore challenges her friend to produce and sell a keychain which is identical to a new, patented keychain which has just come on the market. If Meagan has no idea that her actions will induce infringement of a valid patent she is not culpable under §271(b).

In cases of contributory infringement, one crucial question is whether the device assisting infringement is a “staple good” which has many purposes other than aiding in patent infringement. If so, the maker of the device is not liable for contributory infringement under §271(c), which explicitly excludes from its scope any “staple article or commodity of commerce suitable for substantial noninfringing use….” Even if the majority of the use of the staple good will be infringing use, having a “substantial noninfringing use” will save it from §271(c) liability.

In addition, contributory infringement can occur when a party merely makes and sells an item which customers will use in infringement. In these cases, it would be too burdensome to force a patent holder to sue the direct infringers, i.e., the consumers. See Aro Manufacturing Co. v. Convertible Top Replacement Co. 377 U.S. 476 (1964).

Also, it may be that any case of contributory infringement could fall under the induced infringement provision of subsection (b), with courts applying subsection (c) when the only legitimate use is infringement. See Hornbook at 473.

Direct Patent Infringement

In order to make out a case of induced infringement or contributory infringement, one must first establish that there has been a direct infringement of the patent.

Direct infringement, under §271(a) does not require that the infringer had any knowledge of the patent or her infringement thereof; simply engaging in one of the five proscribed activities makes one guilty of infringement. The five acts which are prohibited under this section, when performed without the patent holder’s permission, are:

  1. Making a patented invention.

  2. Using a patented invention.

  3. Offering a patented invention for sale.

  4. Selling a patented invention.

  5. Importing a patented invention into the United States.

Often, the fact that the accused infringer made, used, sold, etc., a product or process is not at dispute in an infringement suit. The issue, rather, is whether that product or process infringes on a valid patent.

There are two essential steps to an infringement case. First, the patent at hand must be interpreted in order to determine what is protected. Second, the defendant’s product or process must be compared to the protected property to determine whether it infringes the patent.

Example: Stan and Kyle create a robot, for which they apply and are granted a patent. When they claim that Cartman’s robot infringes on their patent, Cartman need not deny making his robot.  There is no doubt that Cartman made the new robot (despite his protestations to the contrary) because his mother already told everyone that her sweet little boy had created this wonderful machine. The question is whether Cartman’s robot infringes on a patented invention owned by the other boys.

Claim Construction & Interpretation

Until it is understood precisely what is protected, an infringement claim cannot go forward. Recall that the language of a patent claim must be precise. That precision is important not only in securing the patent but also in successfully preventing others from copying the new invention.

Finding the precise boundaries of the claim is a matter of law which is determined by the judge. See Winans v. Denmead, 56 U.S. 330 (1854); Glaxo Group, Ltd. v. Apotex, Inc., 268 F. Supp 2d 1013 (N.D. Ill. 2003); Markman v. Westview Instruments, 517 U.S. 370 (1996).

The language used in the patent claim, as well as the specification and any diagrams or models of the invention will be relevant to the judge’s decision, as will be the patent prosecution history. Once the scope of the patent has been determined, it falls on the jury to compare the defendant’s product to the properly constructed patent claim. See Arthrocare Corp. v. Smith & Nephew, Inc., 310 F. Supp 2d 638 (D.C. Del. 2004).

Claim construction is a vital part of the process, as applying different meaning to a single word or phrase can lead to different outcomes in the case. In addition to the intrinsic evidence mentioned above (the claim, the specification, etc.), the judge may consider extrinsic evidence (such as dictionaries and expert testimony) in arriving at a decision.

In addition, there are certain “canons of construction” which guide the Federal Circuit in claim construction and interpretation. These include:

  • Patentee as lexicographer: The patentee is free to use words in a new way or to create her own words, so long as the usage is clear and is in the specification. Because patents deal with novel technology, novel terms are often the only way to describe the invention.

  • Specifications used to understand (not vary, limit, or add claims): While the specification is relevant to claim construction (a la Markman, above), the specification should only be used to shed light on the claim, rather than to alter the claim in any way.

  • Claim differentiation: Multiple claims should be read so as to prevent one claim from being superfluous. In other words, each claim of a patent should be read as having a different meaning from any other claim.

  • Claims construed to preserve validity: When two possible interpretations of the claim are possible, one of which would render the claim invalid, the interpretation which preserves the claim’s validity should control. 

This should be enough to drive home the point made in Chapter 6 of this Courseware, that patent filings should be left to those experienced in the art. Claim format and drafting can have effects far beyond those envisioned during the heady days following discovery of a new invention. That is, when the initial dust settles and a new storm begins to brew in the form of an infringement case, the precise wording of the claim as well as the patent prosecution history will have a dramatic effect on the outcome of the case. When that day comes, woe unto the legal professional who negligently drafted the patent claim due to a lack of professional expertise. 

Literal Infringement (the Super Soaker Case)

Once the judge has delineated the boundaries of the patent, perhaps in line with one or more of the canons of construction, the defendant’s product must be compared to the protected property. There are two ways in which infringement can take place here. Either the defendant’s product includes the precise elements of one of the plaintiff’s claims (literal infringement) or the product might include some different, but unsubstantial elements, in which case it would infringe under the Doctrine of Equivalents.

Literal infringement is, well, quite literal. If the defendant’s product lacks even one element included in the patent claim there is no literal infringement. Note that the defendant’s product here is not to be compared with the patented product, but rather with the patent claim. Loctite Corp. v. Ultraseal, Ltd., 781 F. 2d 861 (1985).

The summer of 1993 was particularly hot. At least, it must have been particularly hot somewhere, right? And thanks to Larami Corp. v. Amron, 27 U.S.P.Q.2d (BNA) 1280 (E.D. Pa. 1993) children all across the nation had one more choice in how to cool themselves off. (Note that these parties were also involved in a trademark dispute: Larami Corp. v. Amron, 1994 U.S. Dist. LEXIS 9453 (S.D.N.Y. 1994).)

While the name Larami might not be a household word, parents of youngsters will likely be familiar with the Super Soaker line of water guns made by that company. The court reiterated the rule that the patent holder must show that every element of the patent claim is in the accused product, and that if even one element is missing there will be no literal infringement. Although the procedural posturing of the case makes Larami the plaintiff here, the patent owner was Amron and Larami was the potential infringer.

The Amron patent claim used the following language:

[a] toy comprising an elongated housing [case] having a chamber therein for a liquid [tank], a pump including a piston having an exposed rod [piston rod] and extending rearwardly of said toy facilitating manual operation for building up an appreciable amount of pressure in said chamber for ejecting a stream of liquid therefrom an appreciable distance substantially forwardly of said toy, and means for controlling the ejection. (Changes in original, emphasis added.)

Crucial here is the word “therein.” The court found that the Larami product had no chamber “therein,” and therefore there was no literal infringement. Instead, the Super Soaker had an external water reservoir. The court made a great deal out of this phrase “chamber therein,” and the decision appears to largely rest upon the fact that the Larami product did not satisfy that element of Amron’s patent claim.

The Super Soaker case is a perfect example of the extremes which must be met in order to make out a case of literal infringement. Because the Super Soaker had a chamber “thereon” and not a chamber “therein,” there was no literal infringement according to the court.

The Doctrine of Equivalents (DOE)

Even when a patent owner cannot show literal infringement of her invention, it might be possible to win an infringement case based on the Doctrine of Equivalents. Citing Lear Siegler, Inc. v. Sealy Mattress Company, 873 F.2d 1422, 1425 (Fed. Cir. 1989), the Laramie court pointed out that the Doctrine of Equivalents is used to “hinder” an “unscrupulous copyist” who avoids literal infringement by being careful not to copy every detail of the patent claim. The court goes on to point out, however, that this is “reserved for the exceptional case.”

The Doctrine of Equivalents (DOE) is a balancing act. On one side of the scales, we must be able to rely on the wording of a patent. On the other side, patent owners must be afforded some level of protection against those seeking to fraudulently and intentionally skirt the bounds of literal infringement. The DOE is a judicially created idea which aims to keep these competing goals in balance.

One test used under the DOE comes from Graver Tank v. Linde Air Products, Co., 339 U.S. 605 (1950). This is known as the “Graver Test,” the “Function-Way Test,” or sometimes the “Function-Way-Result Test.” Whatever we call it, the question is this: Does the accused device function in substantially the same way and achieve substantially the same result as the patented device? If so, it might be an infringing device under the DOE.

Another test used by some courts is the Reasonable Interchangeability Test. Here, a product infringes on the patented device if a “person skilled in the art” (remember that language from our §112 application discussion?) would view the elements as reasonably interchangeable.

As with many doctrines which originate and remain with the courts, the DOE has many different incarnations. Hornbook at 483 discusses the “Insubstantial Differences Test.” Other principles which sometimes play a role in DOE cases include granting broader protection to pioneering inventions and testing for equivalence at the time of infringement (which means that the scope of the patent can change over time). In fact, in Warner-Jenkinson (discussed below) the Supreme Court chose not to prescribe a particular test which courts must apply under the DOE, but instead gave courts the flexibility to conduct their analysis in a way suitable to the case at hand. See also Hornbook at 485.

Limitations on the Doctrine of Equivalents

Because the DOE is meant to balance competing interests (reliability of patent wording against protection from deviousness) its bounds are not limitless.

A leading modern case on the Doctrine of Equivalents is Warner-Jenkinson Co. v. Hilton Davis Chemical Co., 520 U.S. 17 (1997). In Warner-Jenkinson the concept of “file wrapper estoppel” or “prosecution history estoppel” was played out to the disadvantage of the patent owner.

When prosecuting a patent claim, changes are sometimes made in the claim in order to satisfy PTO requests. In Warner-Jenkinson, Hilton Davis had added a limitation to their patent claim in order to distinguish their invention from an existing patent and therefore convince the PTO to issue their new patent. The accused infringing invention in the case, however, would have fallen under the claim as originally written but not under the claim as amended. Because this change was part of the prosecution history, and because this change was apparently vital to the patent being issued, an accused device’s failure to fall under the amended claim prevents that device from falling under the DOE.

Example: Helene is a real estate appraiser and an amateur inventor. She has invented a new camera which takes pictures of subject properties and prints out labels which include detailed lists of the other nearby properties. During patent prosecution, her claim is amended to include the following limitation: “prints labels using ink contained within the camera.” (addition in italics). If a competitor later develops a similar device and Helene sues for infringement, she will fail even under the DOE if the competing device uses ink in a cartridge independent of the camera. After all, the fact that the ink was in the camera appeared quite important in Helene’s securing the patent, so the fact that her competitor’s device does not include this element must also be quite important…this time in distinguishing it as a non-equivalent and noninfringing device.

The idea here is that the applicant gave up the right to claim ownership of anything excluded by the limitation added during patent prosecution, and therefore cannot prevail on an infringement claim which depends on ownership of the excluded element(s).

Before leaving the DOE, we should note the rarely applied “Reverse Doctrine of Equivalents.” The Reverse DOE applies when an accused infringer produces a device which would either literally infringe or infringe under the DOE, but which produces a result so different from the patented device as to be considered a noninfringing invention. See SRI International v. Matsushita Electric Corp., 775 F. 2d 1107 (CA 1985). The principal underlying Reverse DOE is that a patent holder should not be able to stifle dramatic innovations through the PTO-granted monopoly.

Example: Pam Sawnd invents a device which uses a “source of light” to help align pipes in a tunnel. The “source of light” in use is a high-powered flashlight. A few years into the term of Pam’s patent, L.G. Mara makes an identical device which uses a laser as the source of light. This change does not remove L.G.’s device from liability as a literal infringing device. However, because the use of a laser is highly innovative, a court would be loath to prevent L.G. from using her device simply because Pam holds a valid patent. The Reverse Doctrine of Equivalents would apply here.

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