Monday, November 15, 2010

Federal circuit holds structural limitation in method step is limiting despite "comprised" in preamble

Takeaway: In a 1986 claim construction decision, the Federal Circuit held that a method claim which referred to "engaging eight cube pieces" was limited to a 2x2x2 cube despite the use of "which comprised" in the method preamble. Furthermore, the cube size was not expanded by the use of "comprising" in one of the steps: "rotating a first set of cube pieces comprising four cubes about a first axis." The court found that "comprising" was not used as a transitional phrase when describing the first set. Moleculon Research Corp. v. CBS, Inc. (Moleculon II), 793 F.2d 1261 (Fed.Cir. 1986). An old case, but an important one.

Moleculon Research Corp. v. CBS, Inc. (Moleculon II),
793 F.2d 1261 (Fed.Cir.1986)

This is a claim construction and literal infringement case. The method claim at issue involves a solution for what you may recognize as a mini Rubiks' cube.

3. A method for restoring a preselected pattern from sets of pieces... which comprises:
a. engaging eight cube pieces as a composite cube;
b. rotating a first set of cube pieces comprising four cubes about a first axis;

The accused products included the classic Rubik's cube and the super Rubik's cube. The classic cube included 27 pieces (3 x 3 x 3), where you rotate 9 at a time. The super cube included 64 pieces (4 x 4 x 4), where you rotate 16 at a time.

The district court found that even though the larger cubes were not 2 x 2x 2, infringement was nonetheless present because claim used the magic word "which comprises" in the preamble:
Claim 3, and its dependent claims, 4 and 5, read on the 2 × 2 × 2 form of the puzzle, as well as on such larger cubic embodiments as the 3 × 3 × 3 and the 4 × 4 × 4, because it employs the open transitional phrase "which comprises." The term "comprising" denotes a patent claim as being "open," meaning that the recitation of structure in the claim is open to additional structural elements not explicitly mentioned.
(Emphasis in original.)
On appeal to the Federal Circuit, the accused infringer (CBS) argued that "in solving the 3 × 3 × 3 Rubik's Cube or the 4 × 4 × 4 Rubik's Revenge there is no step of 'engaging eight cube pieces as a composite cube'." Infringement is avoided when a method claim's step is "missing" from the accused method. (Amstar Corp. v. Envirotech Corp. 730 F.2d 1476 (Fed.Cir.).)

The patentee (Moleculon) argued that "which comprises" in the preamble allowed for larger cubes:
Moleculon counters that using the transitional phrase "which comprises" not only opens the claim to additional steps, but also opens the claim and its individual method steps to additional structural elements.

The Federal Circuit held that the 3 x 3 x 3 cube did not infringe.

In considering the patentee's argument about the transition in the preamble, the court concluded that "the transitional phrase does not, in the present case, affect the scope of the particular structure recited within the method claim's step." The court didn't find the accused infringer's "missing step" argument persuasive either, noting that the step wasn't missing, merely different.

The court framed the issue as the effect of the structural limitation, within the step, on the cube size:
[Step a] ("engaging eight cube pieces as a composite cube") contains a structural recitation ("eight cube pieces"). The question before us is not whether, because of the transitional phrase "which comprises," the step reads on a step of an accused method which recites additional structure (hypothetically, "eight cube pieces and six metal plates"), but rather whether this step which recites engaging "eight cube pieces as a composite cube" reads on a step which engages more than eight cube pieces as in the 3 × 3 × 3 Rubik's Cube or the 4 × 4 × 4 Rubik's Revenge.

After referring briefly to district court decisions where structural recitations in a method claim step were construed as limitations, the court held that:
[C]laim 3 is limited, at least for purposes of literal infringement, to a method for restoring a 2 × 2 × 2 composite cube. That interpretation follows not only from the language of step (a), but also from the way the eight cube piece composite cube is manipulated in steps (b), (c), and (d). These steps are limited to manipulating sets of four cubes only.
With regard to step (b), the court noted the use of "comprising" in that step didn't help the patentee either because it wasn't used as a transitional phrase:
During oral arguments, Moleculon argued that the word "comprising" in step (b) ("rotating a first set of cube pieces comprising four cubes about a first axis") means that the step covers four cubes or more. "Comprising" is not used here as a transitional phrase and has no special legal effect as such. Hence, it should be interpreted according to the normal rules of claim interpretation. No analogous word precedes the structural recitation of the number of cube pieces in steps (a) and (c). "Comprising" in step (c) reasonably interpreted means "having" but not "having at least."
Having found that the district court's interpretation was erroneous, the court vacated the finding of infringement. However, the court then remanded because the district court didn't make any findings about how the doctrine of equivalents applied to the larger 3 × 3 ×3 cube.

Postscript: On remand, the district court found that the method claims were directly infringed, through the doctrine of equivalents, by users playing the 3x3x3 cube. Moleculon Research Corp. v. CBS, Inc., 666 F.Supp. 661 (D.Del.1987) (Moleculon III). However, the Federal Circuit reversed, finding that the district court's analysis "entirely reads the number of cubelets and their corresponding engagement/rotation out of every step of the claim."

My two cents: I agree with this analysis. I see it as a good case for accused infringers and a bad one for patentees. But the Federal Circuit hasn't always used Moleculon II in this way.

I think the Federal Circuit got Moleculon II right in Spectrum Intern., Inc. v. Sterilite Corp., 164 F. 3d (Fed. Cir. 1998). The court in Spectrum found that a claim did not include additional elements and cited Moleculon II for the proposition that " 'comprising' is not a weasel word with which to abrogate claim limitations."

Yet the Federal Circuit cited Moleculon II years later for the unremarkable proposition that "open language of claim 1 embraces technology that may add features to devices otherwise within the claim definition." Gillette Co. v. Energizer Holdings, Inc., 405 F.3d 1367 (Fed. Cir. 2005). Sure, this is a general statement of the law – that's why I said it was an unremarkable proposition – but it's not really what Moleculon II was about. The court in Gillette went on to find that "a group of first, second, and third blades" could include additional blades because the apparatus preamble used the transition "comprising." That's the opposite of Moleculon II, as pointed out by the dissent in Gillette.

There are differences in the three cases, of course, which can perhaps be used to reconcile them. Moleculon II didn't look to anything but the plain language of the claims to reach its result.  Spectrum reached the same result as Moleculon II after examining statements made during prosecution. Gillette reached the opposite result as Moleculon II after examining the specification, several other claims, and the prosecution history.


  1. So lets get this straight. They're accusing the original Rubiks cube of infringing their method? Mhmmm. Riiiiight. What's the date on this patent? 1960?

  2. Yeah, the patent is quite old, filed in the early 70s. Filing date predates the Rubik's cube, according to Wikipedia.

    My original post didn't highlight the fact Moleculon is an old case.

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