At least one

[TataBox]

Doesn't the use of "or" negate the doctrine of claim differentiation?

[JimIvey]

Doesn't the use of "or" negate the doctrine of claim differentiation?

Hmm.  How so?

Regards.

[khazzah]

klaviernista said
>So, in my view, arguing that the term "a" means "one, or more than one"
>introduces an ambiuguity into the claim language which would require resolution
>by a court in a markman hearing.  Using the term "at least one" largely avoids
>that issue, with little to no alteration (hopefully) to the applicants intended
>meaning.

I'm a little late in joining the conversation, but I'll throw my 2c in.

How likely is it that the commonly-accepted phraseology A WIDGET will be in dispute at the Markman hearing? Yeah, I know that attorneys will argue about almost anything, but really...they're going to argue about whether or not "a widget" covers two widgets? I've read a few claim construction opinions/briefs/contentions, and don't recall seeing one where "A" was at issue.

Readability is the main reason that I don't use AT LEAST ONE. When AT LEAST ONE is combined with a strict application of antecedent basis,  the result is "the least one widget" appearing in my claims a dozen times. Makes it harder to read.

As a side note, I don't know that I would say "a" MEANS "one or more than one". I would say instead that "an infringing device that includes more than one widget still reads on the 'a widget' element".