On Jan. 3, the Patent Trial and Appeal Board ruled that a claim constructed as “at least one of [A] and/or [B]” clearly covered combinations including A alone, B alone, and A and B in combination, overturning an examiner’s rejection that held the claim language indefinite, Ex parte Gross, 2014.

By itself this would merit little discussion, as even a lay reader would  likely  agree  with  the  board’s  understanding  of the language. But in a footnote, the board stated that the “preferred verbiage to claim ‘at least’ clauses of elements A and B would be ‘at least one of A and B’ and not ‘at least one of A and/or B.’” Thus, the board would apparently interpret the claim language “at least one of A, B, C, and D” to claim these elements in the alternative rather than the conjunctive —thus, it would cover A alone, B alone, C alone, B and C together, A and C together, and so on. 

The CFAC, however, has seen this differently. In Superguide v. DirecTV, 358 F.3d 870 (Fed. Cir. 2004), a claim constructed as “at least one of A, B, C, and D” was interpreted to require at least one of each of A, B, C, and D — thus, a combination including only A, B, and C would not fall within the claim scope, and therefore such a combination did not infringe. In deciding this interpretation, the court noted that a previous Federal Circuit decision had interpreted a claim constructed as “at least one of A, B, or C” as covering only A, only B, only C, or any combination of the three, Brown v. 3M, 265 F.3d 1349 (Fed. Cir. 2001).

The Federal Circuit appears to draw a clear distinction between what “and” and “or” mean in claims that list “at least one of” a series of possible elements. The PTAB, on the other hand, apparently accepts the idea that “and” in such claim language can also mean “or.” Is there a genuine disagreement or a more subtle difference between these cases?

As Gross partially highlights, the choice of conjunction when claiming a set of different possible elements may depend on which word will avoid an indefiniteness rejection. Most often it is the use of “or” that causes problems for examiners. Consider a claim for a device that comprises “one of a brake or a locking system.” Because “brakes” and “locking systems” are not equivalent elements, this claim may be rejected as indefinite. By contrast, a claim for a device that comprises “one of a rod or a bar” may pass examination; rods and bars are nearly similar objects performing similar functions that might differ only in their crosssectional shape.

They belong to the same class or category of objects, where “brakes” and “locking systems” do not. The conjunctive “and,” however, is clear in its meaning and unlikely to draw an indefiniteness rejection. This may be part of reason the PTAB advised writing “at least one of A and B” rather than “at least one of A and/or B.”

Adding the “at least” modifier, however, makes the situation fuzzier. If the set of possible elements contains definite and singular items, then the use of “and” versus “or” may be insignificant. For example, a claim to an object “comprising at least one of iron, nickel, cobalt and copper” should imply that “at least one of” modifies the entire set of listed items, not each individual item, because these items belong to a single common category, namely metals. In this case, “and” and “or” would be virtually interchangeable terms. 

But if the set of elements itself lists several categories of items, as was the case in  Superguide, then “at least” would apply to and modify each category in the list, according to the Federal Circuit. Thus, “at least one of an animal, a vegetable, and a mineral” would be interpreted as requiring at least one animal, and at least one vegetable and at least one mineral, as each of these is a broad category of items. Substituting “or” for “and” would instead imply that the claim can be satisfied with one animal, or one vegetable or one mineral, or any combination of the three. 

The difference here is significant, as Superguide illustrates — changing the “and” to “or” in  Superguide’s claim would have prevented DirecTV from finding an easy path to non-infringement. So why didn’t the patentee in Superguide use “or” in the claim language?  Superguide unsuccessfully argued that the patentee was precluded from using “or” in the claim language by then-existing MPEP rules, but had nonetheless intended for the claim to cover combinations that included fewer than all of the listed items, as demonstrated in the written description. 

Yet the court found that every example embodiment in the description supported the interpretation that the claim language unambiguously required one “value” for each of the four listed elements, and found that the rules did not state that the use of “or” was barred, only that the use of “or” might render a claim indefinite. 

It’s difficult to ascertain whether using “or” in the Superguide patent would have actually rendered the claim indefinite because Superguide was unable to provide evidence from the prosecution history to support their claims. The court’s reasoning here, however, suggests there may be situations in which a patent’s description would support interpreting “and” to really mean “or” in an “at least one of” phrase.

Unfortunately,  Superguide does not actually provide much guidance in understanding the PTAB comment in  Gross. The Gross patent application recites a “common parameter including at least one of a common content topic and/or a common contractual arrangement.” If the patentee changed the “and/or” to “and,” as suggested by the board, would the “or” remain implied or would the claim now require one of each of a common content topic and of a common contractual arrangement? 

On the one hand, it seems difficult to argue that “content topic” and “contractual arrangement” are equivalent items belonging to the same category of items; each would appear to be its own category of different types of things. At the same time, the board itself seems to think that using “and” here would imply an alternatives list, rather than a conjunctive list, lending prosecution history support to interpreting “and” to also mean “or” in this case. 

The application’s description is not helpful in splitting the difference; while “content topic” appears in descriptions of the invention’s embodiments, “contractual arrangement” only appears in the claim language, which is mirrored only once in the invention summary, not specifically in any embodiments.

Ultimately the takeaway from this for patent writers, of course, is to be acutely aware of each and every word used in claim language, as even the choice between “and” and “or” may make that least bit of difference between winning and losing on a later infringement action. 

Understand the difference between claiming a list of alternate items within a single category versus claiming a list of alternate categories of items; if the list items could be construed as categories of items as in Superguide, choose conjunctions with caution. At worst, using “or” incorrectly during prosecution may draw an indefiniteness rejection, but using “and” needlessly may be more costly.