Anticipate This!™ | Patent and Trademark Law Blog

To Specify a Further Limitation.

Posted in Practice Commentary by Jake Ward on August 13, 2006

In the recent case of Pfizer, Inc., et al. v. Ranbaxy Laboratories, Limited, et al., a claim was found invalid for being improperly dependent in form.  Pfizer had apparently stipulated at District Court that the claim at issue was a dependant claim and not an independent claim, thus (in hindsight) leaving itself open to the holding in this opinion.  The claim at issue did reference another claim, but was drawn to different subject matter (a hemicalcium salt instead of a compound of claim 1).  I believe this case does prompt the interesting question, therefore, of what actually differentiates an “independent” claim from a “dependent” claim under U.S. patent law?

Conveniently, dependent claims are defined at 35 U.S.C. Section 112, paragraph 4, which states:

          “[A] claim in dependent form shall contain a reference to a claim previously set forth and then specify a further limitation of the subject matter claimed. A claim in dependent form shall be construed to incorporate by reference all the limitations of the claim to which it refers.”

Thus, a dependent claim has two elements:  (1) the claim must contain reference to a previous claim, and (2) the claim must specify a further limitation to the previous claim.

The first of these elements is easily recognized . . . just a mere reference to another claim will suffice.  But what does it mean to “specify a further limitation?”  Does almost any reference coupled with additional subject matter act as a limitation, or can a claim actually reference another claim without providing a further limitation?  For example, does a claim that states “An article prepared according to the process of Claim 1” act to further limit the process of claim 1 by reciting a particular article made by the process, or does it instead recite independent subject matter, i.e. an article and not a process, and thus should be considered an independent claim?

I am of the view that almost any reference (there may be a few exceptions) to another claim results in the claim becoming dependent in form, regardless of whether the new claim is drawn to different subject matter.  I see language drawn to different subject matter, but presented in such as fashion, as a further limitation of the independent claim.  I believe the better practice is to write such claims in truly independent form, especially if it is the intent that the claims be viewed as such. 

I know of some colleagues who disagree with this viewpoint, and feel that referencing another claim but reciting different subject matter makes the claim independent, in particular because they do not view the recitation of different subject matter as a limitation.  Any other practitioners out there feel strongly about this topic one way or another?  Thoughtful comments are welcomed.

2 Responses

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  1. Mark Scott of the Most Excellent Patent Law Firm: Harness, Dickey & Pierce said, on August 14, 2006 at 4:15 pm

    Although Pfizer may not have been in a position to argue that their claim 6 was an independent claim and not merely a different-subject-matter-class dependent claim, a number of practitioners I have worked with do make use of a claim type that is alternately referred to as an independent claim having an internal dependency, or a different-subject-matter-class dependent claim. One common example can be depicted as:

    1. A polypeptide comprising an amino acid sequence according to SEQ ID NO:1, or an amino acid sequence at least 70% homologous thereto, or a conservative substituted variant thereof.
    10. Nucleic acid or nucleic acid analog comprising a base sequence that encodes a polypeptide according to Claim 1, or nucleic acid or nucleic acid analog comprising a base sequence complementary thereto.

    MPEP § 608.01(n) gives other examples, such as:

    1. Product X.
    10. A method for making the product according to Claim 1.
    1. A method for making Product X.
    10. A Product X made by the method according to Claim 1.

    According to the MPEP, such claims are to be counted, at least for fee purposes, as dependent claims, in spite of their apparently not further limiting the subject matter incorporated from Claim 1.

    So, such a different-subject-matter-class dependent claim will be construed either: (1) as a proper independent claim, since it does not attempt to further limit the subject matter incorporated from the prior claim; or (2) as an improper dependent claim for failing to further limit the subject matter it incorporates from the prior claim.

    If such a claim is to be treated as a dependent claim for all purposes, then the logic of Pfizer v. Ranbaxy would lead to its being construed as an improper dependent in every case, under 35 USC § 112, para. 4, unless it also recites an express limitation on the incorporated subject matter.

    In light of this issue, I spoke earlier today (August 14th) with the PTO Office of Patent Legal Administration [(571) 272-7701]. Their representative said that they are aware of the Pfizer v. Ranbaxy case and are currently reviewing the impact, if any, it may have on their practices & procedures, including any possible impact it may have on MPEP § 608.01(n). Although, they could not release any advice or guidance at this time, as to whether an independent claim having an internal dependency will be treated as a viable claim type, or as an improper dependent claim, the representative did provide the statement that “previously the PTO has rejected” dependent claims that do not further limit the subject matter incorporated from the prior claim from which they depend. (Please be aware that the PTO’s treatment of such claims has not been uniform, as many have been allowed; see, e.g., Claim 9 of US 7,041,792.)

    The legal landscape remains unclear on this issue. So, until the PTO can provide further guidance, I suggest avoiding use of this claim type in utility applications.

  2. stewart said, on March 13, 2008 at 5:05 am

    This is very informative, however, I have just re-read the MPEP and the guidance seems to still relate to exclusively to charging – has there been any official chnage due to this decision?

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