Saunders competes with the defendants in the market for relatively inexpensive and lightweight cervical traction devices. Cervical traction is a physical therapy treatment in which a device is used to generate a sustained force pulling upward on the patient’s neck so as to relieve pressure on enflamed or enlarged nerves. The devices at issue in this case allow patients to treat themselves at home.

The problem '690 solved involved improved pneumatic cylinders.

In a combined claim construction and summary judgment opinion, the district court held that the term “pneumatic cylinder” in claim 1 is limited to pneumatic cylinders containing at least one pressure activated seal. The court noted that the specification “only disclosed one embodiment for the internal workings of the claimed pneumatic cylinder” and that the specification “teaches no alternative means by which the pneumatic cylinder can maintain the required traction force.”... Because Saunders admitted that the accused devices do not use pressure activated seals, the court granted summary judgment of noninfringement.

Saunders appeal was on unjustified limitation of "pneumatic cylinder" to having "pressure activated seals."

On appeal, Saunders argues that the district court improperly limited the scope of the term “pneumatic cylinder.” Saunders contends that the term “pneumatic cylinder” does not inherently require the presence of a pressure activated seal and that nothing in the specification or the prosecution history suggests that the term pneumatic cylinder, as used in the patent, requires such a seal. For that reason, Saunders argues, claim 1 of the ’690 patent reads on the accused products, which have pneumatic cylinders without pressure activated seals.

Claim terms are generally given the meaning those terms would have to a person of ordinary skill in the art. Phillips v. AWH Corp., 415 F.3d 1303, 1313 (Fed. Cir. 2005) (en banc). It is not disputed that the ordinary meaning of the term “pneumatic cylinder” does not require the presence of pressure activated seals. The asserted claims can be assigned a narrower scope only if there is some indication in the patent or the prosecution history that the term pneumatic cylinder was meant to have a more restrictive meaning as used in the patent, or a broader meaning was disclaimed during prosecution. See Phillips, 415 F.3d at 1316; Honeywell Int'l, Inc. v. ITT Indus., Inc., 452 F.3d 1312, 1319-20 (Fed. Cir. 2006); SciMed Life Sys., Inc. v. Advanced Cardiovascular Sys., Inc., 242 F.3d 1337, 1342-44 (Fed. Cir. 2001). We conclude that the text of the ’690 patent and its prosecution history do not justify such a restrictive construction of the term.

The doctrine of claim differentiation was key to broadening claim scope: the explicit inclusion of pressure activated seals in a dependent claim provided inference of broader construction in the independent claim lacking such mention.

Given that claim 6 adds the pressure activated seal limitation to claim 1, the doctrine of claim differentiation supports the inference that claim 1 encompasses cylinders without pressure activated seals. Otherwise, claim 6 would add nothing to claim 1 and the two would cover identical subject matter. See Phillips, 415 F.3d at 1314-15 (“[T]he presence of a dependent claim that adds a particular limitation gives rise to a presumption that the limitation in question is not present in the independent claim.”); Liebel-Flarsheim Co. v. Medrad, Inc., 358 F.3d 898, 910 (Fed. Cir. 2004).

The prosecution history was also supportive, in that claims had variously included or left unmentioned pressure activated seals.

Saunders had successfully petitioned to accelerate examination (make special) because of accused infringement.

The Petition to Make Special is also significant because the applicants asserted in that document that a device lacking a pressure activated seal infringed the independent claims of the application.

The defendants argued that there was no mention of pneumatic cylinders that were without pressure activated seals. But single-embodiment disclosure doesn't necessarily limit claim scope without some disclaimer. Sometimes silence is golden. Further, the CAFC reemphasized the value of claim differentiation in being supportive of broader construction.

Because the specification does not describe any pneumatic cylinders without pressure activated seals, and because the specification does not disclose any other way to maintain the necessary traction force, the defendants argue that a person of skill in the art would understand that a pressure activated seal is necessary to maintain the recited traction force. Accordingly, they contend that the claims must be limited to pneumatic cylinders with pressure activated seals.

A patent that describes only a single embodiment is not necessarily limited to that embodiment. Liebel-Flarsheim, 358 F.3d at 906 (citing cases). “Even where a patent describes only a single embodiment, claims will not be read restrictively unless the patentee has demonstrated a clear intention to limit the claim scope . . . .” Innova/Pure Water, Inc. v. Safari Water Filtration Sys., 381 F.3d 1111, 1117 (Fed. Cir. 2004) (internal quotations omitted). While an assertion by the patentee that using pressure activated seals is the only way to maintain the needed traction force would evidence an intention to narrow the scope of the independent claims, the patent contains no such assertion.

While the restrictive language of the specification might be sufficient in other contexts to limit the scope of the claims, it is not sufficient in this case, where the language of the claims so clearly distinguishes between those claims that require the presence of a pressure activated seal and those that do not. See Liebel-Flarsheim, 358 F.3d at 908.

The prosecution history leading to '690 was extensive, going through a continuation of an earlier granted patent (6,506,174). The defendants tried to pin the limits of the parent on the child. But child '690 claims were different than its '174 parent.

The fact that the prosecution history relied upon was created in connection with the parent application would be unimportant if the claim language at issue were present in both patent applications. In this case, however, all the claims in the ’174 patent explicitly require at least one pressure activated seal while the ’690 patent omits that language from the asserted claims. At the same time, the alleged disclaimer distinguishing the prior art focused on a particular claim limitation—the “pressure activated seal” limitation found in each of the claims of the ’174 patent—and was not directed to the invention as a whole. See SciMed Life Sys., 242 F.3d at 1343-44. When the purported disclaimers are directed to specific claim terms that have been omitted or materially altered in subsequent applications (rather than to the invention itself), those disclaimers do not apply. Ventana Med. Sys. v. Biogenex Labs., 473 F.3d 1173, 1182 (Fed. Cir. 2006) (“[T]he doctrine of prosecution disclaimer generally does not apply when the claim term in the descendant patent uses different language.”); Invitrogen Corp. v. Clontech Labs., Inc., 429 F.3d 1052, 1078 (Fed. Cir. 2005) (“[T]he prosecution of one claim term in a parent application will generally not limit different claim language in a continuation application.”); Advanced Cardiovascular Sys. v. Medtronic, Inc., 265 F.3d 1294, 1305-06 (Fed. Cir. 2001) (omitting the claim term to which the prosecution history disclaimer argument was directed precluded those statements from being applied to the child application). Accordingly, any arguments in the prosecution history of the ’174 patent that distinguish prior art based on the presence or absence of a pressure activated seal are inapplicable to the ’690 patent.

The district court had reasoned that a broader construction would render the claims not enabled, thus invalid. The CAFC said that logic was flawed; the patentee had a right to be reckless in what was asked for; validity analysis could not serve as a basis for narrowing claims.

In light of the structure of the claims (with some reciting pressure activated seals and others lacking that limitation), the focus of the Petition to Make Special on the defendants’ device, and the absence of any clear disclaimer in the specification or the prosecution history, we hold that the term “pneumatic cylinder,” as used in the ’690 patent, encompasses cylinders that do not use pressure activated seals, and that claims 1 and 16 are not ambiguous. For that reason, it was error for the district court to use the possible invalidity of those claims, if broadly construed, as a basis for construing them narrowly. See Liebel-Flarsheim, 358 F.3d at 911. That is not to say that we reject the district court’s validity analysis; we hold only that the court’s validity analysis cannot be used as basis for adopting a narrow construction of the claims. Instead, any validity issues that the defendants have preserved and wish to press can be addressed on remand, as was done in the Liebel-Flarsheim case. See Liebel-Flarsheim Co. v. Medrad, Inc., 481 F.3d 1371 (Fed. Cir. 2007) (holding invalid claims that had been given a broad construction at the patentee’s behest in an earlier appeal).

The CAFC offered no scolding, noting the intricacy and complexity that may arise in claim construction; an argument for a specialized patent court circuit.

While we reverse the district court on the issue of claim construction, we do not suggest that the resolution of the claim construction issue presented in this case, or in other similar cases, is easy or that the outcome is dictated by the straightforward application of patent law principles. Cases such as this one, in which predecessor applications or patents were drawn to narrow claims and in which the claims in the successor application are arguably broader than the invention described in the specification, present difficult questions of both claim construction and validity. Where the applicant expressly and unambiguously states his intention to claim broadly, the claim construction issue is easier and the question becomes one of validity—whether the specification supports the full breadth of the new claims. On the other hand, where—as in this case—the patentee has not been explicit about the scope of the new claims, the case can pose interdependent problems of both claim construction and validity.

[T]he problem is a difficult one, made more so by the failure of applicants to state expressly to the examiner, whether for tactical reasons or otherwise, the extent to which they intended their new claims to depart from the scope of the claims in the predecessor applications. In many such cases, as in this one, we and the district court are required to draw sometimes conflicting inferences from different sources of guidance as to proper claim construction and to weigh those conflicting inferences in reaching a conclusion as to the proper construction. After engaging in that process in this case, we reach a different result from that reached by the district court, but not easily.

The defendants wanted a dispositive ruling from the appeals court, arguing noninfringement in at least one instance even with the broader construction. The CAFC demurred from that task, leaving issues of infringement for resolution on remand.