Soon, the Supreme Court will tackle issues about interpretation of patent claims, in Nautilus, Inc. v. Biosig Instruments, Inc. (U.S., No. 13-369, review granted 1/10/14). There are some excellent analyses available, such as “High Court to Review ‘Insolubly Ambiguous’ Indefiniteness Standard for Patent Claims” on Bloomberg BNA, which includes links to the petition for writ of certiorari, the original case and an earlier case that set the court’s standard. See also “Leveling the Culinary Field: Typographical Corrections in Markman Ruling Allow Food Service Equipment Leveling Device Patent to Be Construed”, by Kirk Watkins of our firm Womble Carlyle Sandridge & Rice, which article discusses claim indefiniteness in reference to the above case. One of the issues the Supreme Court will be reviewing is, what is the meaning of the claim term “spaced relationship”? How is this meaning determined? Rather than repeat further information from the petition or other sources, which the interested reader is encouraged to review, let’s take a look at some other examples of claim terms that might be construed as ambiguous and that could prove troublesome if not clearly supported in the specification of a patent application. In other words, let’s expand our awareness to the greater issues. How might we better write (and illustrate) specifications in patent applications, so that examiners and courts can better determine the meanings of claim terms?
Orientations of elements and physical relationships among elements are frequently recited in claims. A claim element that is vertical, horizontal, sloping, inclined, level, or in parallel relationship with, in perpendicular relationship with or in staggered relationship with another element, or is skewed, aligned with or otherwise related to another element might seem completely clear, as claimed, to the Applicant. However, unless the patent application shows (in drawings) and describes (in the detailed description) what these claim terms mean, the claim terms could be construed in a manner counter to the intentions of the Applicant. For example, rotate a device by 90 degrees, and suddenly what was vertical is now horizontal. Tilt it, and what was level is now sloping.
Couplings and connections can be troublesome. An element that is coupled to or connected to another element, and claimed as such, could mean many things. Is the element physically coupled? Electrically coupled? Directly coupled, indirectly coupled, coupled via some third element? Could further elements be involved in the coupling or connection? This is particularly difficult to claim unambiguously with electrical or electronic circuits, in which two elements could be coupled via multiple paths. In a mechanical invention, is the coupling rigid, flexible, pivoting, removable, conditional or otherwise?
The inclusion of multiple embodiments in a specification is generally wise, as this helps define the scope of the claims. Yet, do we always put multiple embodiments for each coupling or connection, or type of element that could be coupled or connected to each other element, and so on? Given the mathematical possibilities for combinations, it is generally not possible to include in a specification of a patent application every imaginable combination of elements that could give rise to equivalents, examples and embodiments.
Materials and layers can be difficult to describe and claim. What is a layer? Does a layer include further layers, or is this layer the only such layer? Does the sequence of layers matter? When is a layer adjacent to another layer? Could two layers that are adjacent nonetheless have another layer between them? Is a layer a composite layer? When is a layer “thin” or “thick”? Using relative terms, such as one layer being thicker than another layer, can be useful here.
A giant caveat concerns exclusionary claiming. When something is excluded, to what extent is it excluded? The answer might seem entirely clear: the element is entirely excluded. But even that is not always the case. Claiming that one element is decoupled from another element could be interpreted correctly with respect to a specified and claimed coupling device, but, for example, there could be other elements that are coupling the two elements. So is the one element truly decoupled from the other element? Drawings and written description can help clear up this ambiguity in the claim language. A good strategy could also include explicit claim language covering the above aspects of this ambiguity.
Although an observant Examiner may call attention to ambiguity in claim language by rejecting claims during prosecution as allegedly indefinite, some may let ambiguity slide. Some patent practitioners prefer to construct claims with as little ambiguity as possible, so as to attempt to proceed through patent examination with fewer claim amendments. Some patent practitioners prefer to construct claims with some ambiguity, so as to have flexibility during patent examination. In either event, amendments to the claims can be added to clarify the meaning of claim terms.
In all of the above examples, ambiguity in claim language can best be resolved by support in the specification. So, when writing claims, it is best to cast a critical eye at each term in the claims, and ask, is there any ambiguity in this claim term, and what support does the specification contain for resolving any such ambiguity? This is all part of the art of patenting. I’m sure you can come up with examples of other possibly ambiguous claim terms.