The Federal Circuit has issued yet another ruling that looks at computer-based means-plus-function claims and finds them wanting. The message is unmistakable: Practitioners must adjust their approach toward writing claims for computer-based inventions.

A standard means-plus-function clause in a patent claim defines a product not in terms of structure, but in terms of what the structure does. Instead of claiming “nails, screws or glue,” one can instead claim “fastening means.” One of the requirements of means-plus-function claiming is that the specification, as opposed to the claims, must disclose a structure for performing the claimed function.

Failure to do so renders the claim invalid for “indefiniteness.” Thus, in the “fastening means” example, at least one fastening structure must be disclosed in the specification, even if those of ordinary skill would already know of such structures without such a disclosure.

In the case of computer-based inventions, the Federal Circuit has long held that merely disclosing a general purpose computer or “programming” is not enough. Instead, one must disclose an “algorithm,” showing the steps by which a programmed computer performs the claimed function. Failure to do so “amounts to impermissible pure functional claiming” and invalidates the claim.

The Federal Circuit’s recent decision in Ergo Licensing, LLC et al. v. Carefusion 303, Inc. dealt with an invention for an infusion system used to deliver fluids to a patient. One of the non-inventive parts of the system was, as stated in the claim, “programmable control means.” Ergo, the patent owner, told the court this was “the structure with which control and monitoring functions can be performed,” and further argued it was a computer with appropriate programming.

However, the court believed the specification disclosed only an undefined “control device.” The court rejected Ergo’s argument that “control device” simply means a computer, holding that even if it did mean “a computer,” that is insufficient because no algorithm was disclosed.

Although this decision appears to be based on solid Federal Circuit precedent, Judge Pauline Newman vigorously dissented. To her mind, the specification did disclose “the function and operation of the control device” sufficient to meet the means-plus-function claiming requirements, and she chided the majority for not acknowledging it.

She also put great emphasis on the fact that the “control device” is not itself the claimed invention, as there is nothing special or nonobvious about it. Indeed, anyone of ordinary skill “could routinely instruct the control device how to perform the described control.”

Judge Newman’s dissent illustrates her view that the Federal Circuit is applying its “algorithm rule” in a “purely formalistic” fashion. She rebukes the court for its foray into “patent draftsmanship, finding standard presentations [of claim elements] now to be fatally deficient,” and notes that “thousands, perhaps hundreds of thousands, of issued patents” are written in similar fashion. “The court’s new position simply taints thousands of heretofore innocent patents.” This is a “disservice to inventors” and an “injury to the public,” all in an area in “which the expertise of patent examination is normally superior to that of judges.”

Whether the court has simply applied the law as it already stands, or has taken a “new position,” as Judge Newman asserts, it is clear that means-plus-function claiming for computer-related inventions will be exposed to increasing scrutiny. The specification can now be expected to limit severely the ability to obtain valid claims with means-plus-function clauses.

Such claiming remains an important tool in the patent drafter’s arsenal, and indeed means-plus-function claims may in some circumstances still be the best way to claim structure without relying solely on method claims.

However, the judicial dissection it attracts suggests that it be used to supplement other types of claims, such as structure or method claims. That way, even if the means-plus-function claim is found invalid, the other claims may remain to be asserted.