Any extra word in a claim "can and will be used against you in a court of law." Thus on the one hand, recitations in a detailed preamble may unduly limit the claim in unintended ways. By contrast, a generic preamble can never get you in trouble in that regard.
On the other hand, detailed-preamble claims can serve any number of useful purposes. The trick is to draft detailed preambles with our eyes open.
The pivotal issue is not the length of the preamble, per se, but coming to grips with what legitimate function (if any!!) is served by any particular preamble detail—be it a single word, a phrase or a whole paragraph.
It is important to note that a claim's preamble limitation can be deemed limiting when one goes to enforce the claim, even though the preamble limitation was given no patentable weight during prosecution, and thus did not help to secure the claim's allowance. Such a preamble limitation will have given up claim breadth without having received anything of benefit in return.
Consider the following claim to an automobile floor mat.
An automobile floor mat comprising
a semi-rigid monolayer having a gradually sloping edge portion extending outward from a central section, said edge portion terminating in a lip disposed at an elevation above the central portion, the lip having a plurality of indentations disposed a regular intervals around its periphery.
There is nothing in the body of this claim that requires the claimed structure to be an automobile floor mat. Thus an examiner may well regard "automobile" as being a mere statement of intended use and may reject the claim based on prior art disclosing the claimed "semi-rigid monolayer" whether or not the prior art structure was designed for use in an automobile. Or intended to be placed on a floor. Or perhaps even whether it was intended to be used as a mat.
Suppose, on the other hand, that there is no such prior art, so that the claim is allowable as presented above. Although the descriptive label "automobile" was of no help in securing allowance of this claim, it may come back to bite the patent owner when asserting the claim against suppliers of locomotive cab mats that cannot be used in automobiles (because, for example, they are too big). The patent owner will argue that the term "automobile" should be given no limiting effect because it is not necessary to give "life, meaning, and vitality" to the claim. Pitney Bowes, Inc. v. Hewlett-Packard Co., 182 F.3d 1298, 1305, 51 USPQ2d 1161, 1165-66 (Fed. Cir. 1999). That argument may or may not carry the day, depending on how the Markman judge understands what the gives-life-meaning-and-vitality test actually means and how that test applies to the invention at hand.
In any event, the Opposing Team will have a field day with this claim, hammering on the notice function that a patent's claims are supposed to serve and arguing that "if the applicant didn't intend to be limited to automobile floor mats, why did he put it in the claim?" The prosecuting attorney makes the job of the licensing/litigating attorney all the more difficult by opening the door for such an argument to even be raised.
Drafting this claim with a generic preamble, viz.,
A manufactured article comprising,
a semi-rigid monolayer…
may thus save everyone a lot of grief. Indeed, it may save the day.
Descriptive labels and modifiers, such as "automobile" and "floor" in the above example, should always be suspected as creating an infringement loophole without providing any countervailing patentability benefit. Other "usual suspects" are advantages and/or intended uses of the invention. Indeed, the reader should have little trouble in conjuring up reasonable technological embodiments in which claims having the italicized preamble language could be argued to be non-infringing even if the limitations of the body of the claim are met:
An optical system in which at least two out of phase light beams of different frequencies are combined with improved output efficiency, the system comprising…
An on-chip debug system for a programmable VLSI [very-large-scale-integration] processor, the debug system comprising…
A high speed rotor of a type applicable for use with a flywheel, the rotor comprising [no flywheel mentioned in the rest of the claim]
This is not to say that a detailed preamble is necessarily a bad thing. For example, certain intended-to-be-limiting recitations sometimes fit better in the preamble than in the body. In that situation, recitations that call out to be placed in the preamble during the course of the drafting the overall claim invariably tie into other limitations in the claim body and/or replicate them explicitly. Such preamble recitations will thus certainly give life, meaning and vitality to a claim and thus can be effectively relied upon in arguing the claim’s patentability.
Below is a claim that uses Dennis’s exemplary detailed preamble. Note how every limitation in the preamble ties into the body of the claim.
A method for content selection of digital media stored in a memory…, the method comprising,
assigning an individual portion of the digital media to a particular portion of the memory based on whether or not the content of that portion includes video data,
selecting one of the individual portions by …..
It is helpful to start out with a generic limitation, and not packing a limitation into the preamble until the structure of the evolving claim makes it clear that it is needed there. This helps protect the preamble from details that can only hurt and not help.
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