Patent claims define the scope of an invention much like metes and bounds define real property boundaries or a statute delineates the difference between criminal and non-criminal activity. Often, patent applicants submit a series of claims all directed toward the same invention. Various independent claims allow an applicant to focus on various aspects of the invention. These broad aspects may be directed to various nodes of a larger system or regions of a compound, processes for creating or using various elements, etc. Dependent claims by definition add additional limitations. Thus, for instance disputed claim 1 and 2 from the recent Lovanex dispute reads as follows:
1. A heterogeneous intimate admixture of sulfated heparinic polysaccharides … consisting essentially of
from 9% to 20% of polysaccharide chains having a molecular weight less than 2,000 daltons
from 5% to 20% of polysaccharide chains having a molecular weight greater than 8,000 daltons, and
from 60-86% of polysaccharide chains having a molecular weight of between 2,000 and 8,000 daltons ….2. The heterogeneous polysaccharide admixture as defined by claim 1, comprising less than 2% of dermatan sulfate.
Claim 2 is interpreted to include all the limitations of claim 1 with the additional limitation of “less than 2% of dermatan sulfate.” See 37 CFR 1.71(c).
Earlier this week, I polled Patently-O readers on why they file dependent claims and received just over 1000 responses. (Listed below).
| Theory of Dependent Claims | ||||||
| Why do you file dependent claims? | ||||||
| Percent of Responses | ||||||
| Answer Options | Strongly Agree | Mostly Agree | Neither Agree nor Disagree | Mostly Disagree | Strongly Disagree | Rating Average |
| Dependent claims are backup in case the independent claim is rejected in prosecution. | 59% | 34% | 4% | 2% | 0% | 1.51 |
| Dependent claims are backup in case the independent claim is found invalid in litigation. | 59% | 31% | 6% | 3% | 1% | 1.56 |
| Claim Differentiation: The dependent claims expand or alter scope of other claims. | 47% | 37% | 8% | 6% | 3% | 1.82 |
| Dependent claims focus on particular commercial embodiments to make infringement easier to explain to a jury. | 29% | 44% | 21% | 4% | 2% | 2.07 |
| I primarily include dependent claims with nonobvious additional limitations. | 19% | 45% | 25% | 9% | 1% | 2.29 |
| I was taught to draft dependent claims. | 26% | 34% | 26% | 8% | 7% | 2.35 |
| USPTO fees: Patent office does not charge extra for first twenty-claims. | 26% | 34% | 24% | 9% | 7% | 2.36 |
| Dependent structure better supports foreign filing. | 7% | 19% | 58% | 11% | 3% | 2.84 |
| Dependent claims are easier to draft and manage than independent claims. | 6% | 23% | 37% | 23% | 11% | 3.08 |
| Client demands a certain number of claims. | 6% | 16% | 29% | 25% | 23% | 3.42 |
| Dependent claims help avoid restriction requirements. | 2% | 13% | 39% | 31% | 15% | 3.44 |
| A longer application is more valuable. | 2% | 13% | 29% | 34% | 22% | 3.60 |
| answered question | 1029 | |||||
| skipped question | 0 | |||||
Responses were also allowed to add additional reasons in the comment section. I have compiled a few of those individual responses below.
- Drafting Process: A few responses commented on the iterative process of drafting a patent. For some, drafting the dependent claims helps refocus and redefine potentially problematic terms from the independent claims. For many, the dependent claims also serve as a guide for fully drafting the specification.
- Prosecution Process: Some responses proposed that the dependent claims are helpful during prosecution for several reasons. First, there is a perception amongst patent practitioners that examiners read and consider the claim-set before looking at the actual specification. For that reason, the claims should be considered as a way to teach the examiner about the features and purpose of the invention. For some, obvious limitations in a dependent claim are useful in that regard to show the examiner an intended use (practical embodiment) of the invention. For those who see patent prosecution as a negotiation, a series of narrowing dependent claims speed up the the process — the applicant and examiner need only agree upon how narrow the claims need be. Some propose at least some dependent claims being “super narrow” to serve as a “foot in the door” to increase the likelihood that there is at least some patentable subject matter. Once you have agreed that a patent will issue, it may be easier to debate the scope of the eventual claims. On a practical note, the existence of dependent claims means that an applicant can get to a post-final rejection allowance without filing a request for continued examination. These practical concerns are important considering that the vast majority of patent applicants amend their claims during prosecution.
- Claim Differentiation: Most practitioners agreed that the claim differentiation benefit of dependent claims is important. The doctrine encourages courts to consider that each claimed element covers something different than the others. Pushing that line, a typical reasoning is that two or more dependent claims providing alternative implementations of a term from an independent claim will help ensure that the independent claim element is not limited to a single embodiment. Some folks quibbled with my statements regarding dependent claims “expanding scope” of other claims and instead used a more PC version of “aiding construction.” It is important to realize that the originally filed dependent claims also form part of the specification and can thus help overcome enablement and written description hurdles.
- Appeasing Clients: Many inventors see their invention narrowly — as their particular embodiment. Dependent claims provide an easy way to satisfy the inventor’s desire to claim their invention without limiting legal rights. On this “politics” side — dependent claims also give reason to add joint inventors, which may be good for office politics. “An invention may only warrant one independent claim embodiment, but many clients like to see many claims. They believe the more claims they have the stronger the patent and that they are getting value for there money.So you add them, e.g., a blue widget, a red widget. It is like chicken soup for a cold, it can’t hurt.”
- Ease of Analysis: “Filing dependent claims rather than only independent claims makes it much easier for several parties (attorneys prosecuting the application, examiners and the BPAI examining the patent, attorneys analyzing the issued patent, courts analyzing the issued patent) to more readily evaluate the differences and similarities of claims.” Others noted that it is also useful as a way for potential licensees to know that the proposed product is literally and explicitly covered. For some patent owners, this “ease of analysis” is actually a negative. (Try to read NTP’s $600,000,000 claims). A long claim-set makes it more likely that a potential defendant will easily cave rather than pursue an expensive invalidity / noninfringement study.
- Capture “minor inventions”: Dependent claims allow an applicant “to capture improvements to the invention that are not important enough to justify a separate application, but that one would want to avoid having a competitor step in and patent something similar.”
- Tradition: There is nothing wrong with tradition and custom. It helps ensure that we’re all on the same page. For many the 3/17 rule of independent/dependent claims serves as a default rule that can be adapted for unique circumstances.
- International: Internationally, patents use fewer independent claims than in the US. One European attorney made the following comment: “Multiple independent claims in the US style cause major headaches and costs in Europe, so one good independent, with well gradated dependents, is the best solution for me.”
- I will attach the full comments once reformatted.