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There are a few things that keep patent attorneys up at night and one of them is the choice of words when drafting a claim. Sometimes “one word” can make all the difference to the enforceability or validity of a patent.

This is a general information article meant for a non-legal readership so it may be useful to set the scene. When an inventor brings their idea to an attorney one of the many tasks but one of the most important is to define the invention. A claim is a one-sentence definition of the crux of the invention, which must be clear and succinct, and supported by the matter described in the rest of the specification. There will only be the minimum number of essential features in the claim. The claims of a patent define the invention to which the patentee is entitled the right to exclude others exploiting.

The words of the claim are carefully chosen to define the invention. However, as is the way of patent opposition or litigation each side will sometimes need the words to have a particular meaning that benefits their position. The other side will argue before the patent office or the court that all or just one of the words has a different meaning to the one the drafter thought it had, especially if the term turns out to mean that the patent is not valid in light of a particular meaning. Then there are times that a phrase or just one word needs to have a meaning that benefits the patent holder to make the alleged infringers’ product or method fall within the scope of the claim. It all comes down to claim interpretation, which is determined by the Hearing officer or the Judge/s as considered through the eyes of the person skilled in the particular art.  Interestingly, not all the Judges in a case necessarily agree but that is a topic for another article.

This article does not include a discussion of all the relevant issues for this topic, such as ambiguity, lack of clarity, or lack of support. Yet further, other related issues include but are not exhaustive: mechanical equivalents, essential and inessential element, etc.

There are many cases to illustrate this issue and the following were of interest to the writer.

Let me illustrate some phrases that did not quite work as the drafter intended.

The US Federal Circuit had to interpret the meaning of the phrase “heating the resulting batter-coated dough to a temperature in the range of about 400° F. to 850° F.” , in particular the term “to” in the wording of the claim was at issue. What should have been said was “heat the oven to a temperature in the range of about 400° F. to 850° F.”, since what was defined by the words of the claim was for the internal temperature of the dough to reach between 400° F. to 850° F. If the dough were heated “to” that temperature range, it would be burned to a crisp. Heating the dough “at” that temperature range supposedly results in a light, flaky, crispy texture, according to the patent’s specification. Even though it would be nonsensical to require heating the dough “to” 400°F, the initial court refused to construe the claims otherwise, and the Federal Circuit on appeal affirmed, which rendered the claims not infringed

The claims to the invention included claims to a “scanner,” where the term “scanner” was not defined in the specification, which simply contained one illustrative embodiment having a moving scanner head. Faced with the question of whether a digital camera qualified as a “scanner,” the court turned to dictionaries and concluded that a scanner required “movement between a scanning element and an object being scanned.” This definition was appropriate because it was on foot with what the patentee had disclosed in the specification as being a scanner.

Of course today there is an app for that (this is meant to be a quip as the detail of the subject patent is not discussed here) so the existence of such an application which can use a digital camera in a mobile phone to take and process an image into a PDF of a page of a document may never have had any influence on the particular claim.

A similar issue arose when a patent claim recited an end user computer “normally connectible to a conventional computer input/output port”. Although the patentee attempted to equate “conventional” with “dedicated” the court focused squarely on the ordinary meaning of “conventional” as limiting the input/output port to technologies in use at the time the patent was filed. The accused infringer employed flash memory and smart cards in practicing the recited process steps, but because those technologies were not known in 1988 (the date of the patent of this US case), summary judgment of non-infringement was affirmed.

In another US Federal Court case circa 1996 the invention before the court related to a method of repairing underground pipes. The method included the steps of inserting a liner into the pipe and then impregnating the liner with resin by applying a vacuum to the interior of the liner, using a cup-shaped vacuum connection operating through a window formed in the liner. The critical claim language recited the resin distribution process including the limitation “wherein the vacuum is applied … by means of a cup” applied to the window. The uncertainty lay in whether the claim covered a system using more than one cup. The Court looked for evidence within the specification that the inventor intended to limit the invention to a single cup as well as the alternative of more than one cup. Unfortunately, the specification only described the use of one cup and did not mention an intention or alternative to use more than one cup. The Court concluded that “the only correct and indeed the reasonable interpretation of claim 1 limits the scope of that claim to a process using only one vacuum cup.

This issue is universal across technologies and not just a mechanical technology phenomenon. In a further US Federal Circuit case in 2008 the technology of the invention was in the field of recording television programs, the claim language required that “the Output Section assembles said video and audio components into an MPEG stream” (emphasis added). The Court determined that the claim and written description make clear that the singular meaning applies, where the actual language refers to “assembl[ing] said video and audio components into an MPEG stream.” It would appear that as distinct from an environment where there are many mechanical parts to a system the provision of a single output stream is part of the invention wherein the MPEG stream is restored to an earlier state, the state in which it was earlier received. Thus the term did not encompass the alleged infringer’s arrangement that involved the use of two different MPEG output streams.

In the same case the term “multitude” was used in the claims the other side contended the term meant that the device must accept more than one type of broadcast signal, being analog and digital, as a minimum, rather than having the meaning that the device could accept “one or more” broadcast signals and could deal with, a single analog or single digital broadcast signal, or both. The Court opined “… it seems unlikely that a claim drafter would use a term of such biblical imprecision as “multitude” if that term were meant to have an important restrictive function in the claim…it is difficult to understand why the drafter would not have used that very common (and clear) manner of expressing the idea.”, when referring to the clearly preferred use of “one or more” rather than “multitude”. In this case the Court decided in favor of the drafter, but the patent challenger (infringer) took the patentee for a ride during the case and the outcome was not necessarily assured for the patentee, all because the drafter chose to use the term “multitude”. There were a number of such determinations in this case the above two being of particular interest.

In another US Federal Court case it was noted that statements distinguishing the prior art must be sufficiently clear to warrant a narrowing construction concerning claims to a method of “dispensing” reagents onto a microscope slide. The question was whether “dispensing” was limited to “direct dispensing” (i.e., where the reagent container directly dispenses reagents onto the slide without an intermediary), or whether the claims encompassed the use of an intermediary device to “sip and spit” the reagents from the reagent container onto the slide. The specification contained general criticisms of prior art dispensers, including those using “sip and spit” approaches, as well as those using “direct dispensing” approaches. Because the specification equally criticized both types of prior art dispensers, there was nothing to suggest that the inventor was describing the invention to be the use of “direct” instead of “sip and spit” dispensing. Therefore, the US Federal Circuit found it was inappropriate to limit the claim scope. This could be seen to be a matter of properly supporting the claim but as always hindsight makes these issues clearer after the event.

In yet another example, the invention was a high-performance double-walled aluminum softball bat. The claim was directed to a bat and recited, “a hollow tubular bat frame having a circular cross-section; and an insert positioned with the frame …” The district court granted summary judgment in favor of the defendant, holding that: (1) the term “frame” as modified by term “bat,” and used in the patent, was a tubular structure having a large-diameter impact portion, a tapered portion, and a small-diameter handle, all of which are connected when the bat is fully constructed; and (2) “insert,” as used in patent, meant a piece of material that was separate from, and completely surrounded by the frame.

The patent owner appealed, arguing that the district court’s interpretation of “bat” as modified by “frame” was improper. The patent owner asserted that the term “bat frame” is a hollow tube that covers the hitting end of the bat and that the “insert” is a structure that incorporates both the handle and the portion of the hitting end of the bat that goes inside the “bat frame.” The Federal Circuit affirmed the district court. The Federal Circuit noted that the claim language did not set forth what structure was described by the “bat frame,” nor did the written description define “bat frame.” Therefore, the court resorted to the ordinary dictionary definition of the term “frame.” The Court then looked at the ordinary meaning in the context of the written description and prosecution history to determine the proper construction of the term in the claims in which it is used. The Federal Circuit interpreted “bat frame” essentially the same as the district court. The Federal Circuit also accepted the ordinary meaning of “insert” and held that the district court correctly interpreted the claim limitation.

So it is, there are many traps for the unwary. This article is a mere toe in the water of the issues that are known to your patent attorney who can provide their expertise while drafting your patent or discuss these issues at any time.