Chapter §15.06 Interpreting Preamble Language

• Jurisdiction: United States

§15.06 Interpreting Preamble Language

[A] Preamble Not Scope-Limiting

The general rule (subject to many exceptions) is that language in the preamble of a patent claim³⁵⁴ is not limiting.³⁵⁵ Where the body of the claim (i.e., the language following the transition) recites a structurally complete invention and the preamble language states only an intended purpose or use for that invention, the preamble language is generally not limiting.³⁵⁶ Language that appears only in the preamble of a claim, not repeated or referred to in the body of the claim, is less likely to be held a limitation of the claim.³⁵⁷ A similar result obtains when preamble language is considered merely laudatory.³⁵⁸ The practical result is that such preamble language does not help preserve the validity of a claim (nor does it have to be met by an accused device in order to have infringement).

For example, the patent in suit in Allen Eng'g Corp. v. Bartell Indus. concerned certain concrete riding trowels used to smooth the surface of freshly poured concrete.³⁵⁹ The preamble and transition of a representative claim recited a "self-propelled, fast steering motorized riding trowel for finishing a concrete surface, said riding trowel comprising. . . ."³⁶⁰ To avoid a potentially invalidating on sale bar, the patentee argued that the preamble phrase "fast steering" should be construed as a limitation of the claims.

The Federal Circuit disagreed, siding with accused infringer Bartell that "fast steering" was simply a laudatory term setting forth the invention's purpose. "Fast steering" was "a relative term, and no interpretive frame of reference [wa]s provided in any of the claims or in the specification."³⁶¹ Nothing in the record indicated that a person of ordinary skill would understand the meaning of "fast steering" without such a frame of reference. Moreover, the preamble phrase "fast steering" failed to give "life, meaning and vitality" to the claimed structure. Thus, the Federal Circuit concluded, the phrase was not entitled to any claim-limiting meaning.³⁶²

[B] Preamble Is Scope-Limiting

In contrast with the previous example, the Federal Circuit holds that preamble language is considered limiting (that is, material to validity and/or infringement) if the language is necessary to give "life, meaning and vitality" to the claim or if the preamble language recites essential structure or steps.³⁶³ In particular, if the preamble terminology is repeated and referenced in the body of the claim, it is most likely limiting. When limitations in the body of a claim "rely upon and derive antecedent basis from the preamble, then the preamble may act as a necessary component of the claimed invention."³⁶⁴ The preamble may be limiting when it recites "additional structure 'underscored as important by the specification.' "³⁶⁵

The preamble language at issue in Bicon, Inc. v. Straumann Co. is illustrative.³⁶⁶ The patent in suit was directed to an apparatus for use with dental implants. The invention involved a plastic cuff designed to preserve a space around a dental implant. More specifically, a dental implant prosthesis of the type contemplated by the patent included (1) a root member implanted in a patient's jaw bone, which root member was attached to (2) an abutment that protruded above the patient's gum line to provide the structure for attaching a crown (the tooth-shaped cap placed over the abutment). Temporary installation of the invented plastic cuff kept the patient's gum tissues from closing around the abutment while the patient's jaw and mouth continued to heal. After healing had completed and the plastic cuff removed, a dentist could take advantage of the space left by the cuff to affix the permanent crown to the abutment at a point beneath the patient's gum line. Affixing the crown beneath the gum line advantageously maintained the natural look of the patient's gum line with the crown installed.

The pertinent claim of the patent recited, with the preamble language emphasized:

5. An emergence cuff member for use in preserving the interdental papilla during the procedure of placing an abutment on a root member implanted in the alveolar bone of a patient in which the abutment has a frusto-spherical basal surface portion and a conical surface portion having a selected height extending therefrom comprising

a generally annular member formed of biocompatible synthetic plastic having first and second ends, a bore extending from the first to the second ends, the bore having a taper generally matching that of the conical surface portion of the abutment, the larger end of the bore being at the first end, the outer surface of the annular member forming a feathered edge with the bore at the first end of the annular member, the distance between the first and second ends being less than the height of the conical surface, the diameter of the cuff member increasing in the direction going from the first end to the second end, and a radially inwardly extending flexible lip formed at the first end of the cuff member. ³⁶⁷

To establish infringement by the accused device, the patentee argued that the preamble's reference to the abutment was not a limitation of the claim but rather merely described the purpose or intended use of the emergence cuff. In other words, according to the patentee, the claimed invention was the emergence cuff only. Use of the cuff on any type of abutment would infringe, whether or not such abutment had the...