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November 17, 2015


How does the DOE apply in this situation and more importantly, when the negative limitation existed in the original claim?

I am curious whether the author has any evidence of the claims that "[m]any" patent attorneys have a "visceral, disapproving reaction" to negative claim limitations. I've never held (nor really heard of) any such prejudice.

To the contrary, negative claim limitations are a legitimate prosecution tool and therefore need to be in the took kit of every competent attorney. If using them is the best way to serve your client's needs under appropriate circumstances, use them -- indeed, you may be ethically obligated to do so. You do your client a disservice if you don't.


Good question, and one that I've probably not thought about enough to answer.

In this case, however, prosecution history estoppel would likely prevent the patentee from arguing for a construction under the DOE that does not include the negative limitations at issue.



"Many" here is a personal anecdote. Older case law took a dim view of negative claiming, but more recently this veil has lifted. Some folks still view it with suspicion. Others think it is a lazy technique to avoid coming up with more creative positive language to achieve the same goal. See my kitchen utensil example above.

Having said that, I've used negative claiming from time to time and have had no issues. But when I review the work of other attorneys, I encourage them to avoid negative claiming unless it is clearly the best way of claiming the invention.


I can think of several "negative" limitations that have often been used and Examiner's have not had a problem with: anhydrous, wireless, no more than, _______-free.

In addition to the older case law that disfavored negative limitations, I think the big hang-up for many Examiners and, as a result, for many patent professions is with using the term "not" in a claim. It just seems wrong somehow.

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