Five Patent Drafting Mistakes That Can End Your Startup

by Bryan DeMatteo, Esq.
November 18, 2015

Startups and small businesses often seek patent protection of their ideas to satisfy venture capitalists, generate licensing revenue, or to carve out a niche in an otherwise competitive marketplace.  However, the ability of a patent to facilitate these goals depends directly on how the patent would fare in litigation, as a patent provides nothing more than a legal right to sue others for infringement.  It is from this threat of suit that all secondary measures of patent value, such as “licensing” and “competitive” value, are derived.

It is thus of paramount importance to draft patents to avoid common pitfalls that often result in patent invalidation or unnecessary findings of non-infringement in a court of law.  Failure to consider potential litigation when drafting a patent may result in unfavorable valuation by venture capitalists, lower licensing revenue and ineffective market protection.  Below are five critical patent drafting mistakes that should be avoided.


It is common for patent drafters to describe embodiments of the invention as “preferred.”  Such a practice was born from a now marginalized legal requirement that a patent describe the “best mode” or “best embodiment” of the invention.  However, identifying embodiments as “preferred” is unnecessary because “best mode” requires only that an inventor disclose the best embodiment, not that he/she identify which disclosed embodiment is the best, much less characterize any embodiment as preferred.  The importance of the “best mode” requirement has also been diminished significantly by the America Invents Act (AIA), which eliminated invalidity defenses based on an inventor’s failure to disclose the “best mode.”

While patent claims are not typically limited to features of preferred embodiments, savvy litigators invariably try to equate preferred embodiments to the invention itself. Such arguments appeal to lay jurors, who often understand “preferred” embodiments as somehow carrying more patentable relevance than others, especially if the accused infringer’s product does not embody a “preferred” embodiment. It may be more advisable to describe embodiments using neutral descriptors that do not communicate that any one embodiment is “preferred” over any other.

Lay jurors … often understand “preferred” embodiments as somehow carrying more patentable relevance than others, especially if the accused infringer’s product does not embody a “preferred” embodiment


Patent claims are often drafted broadly to encompass numerous variants of the invention.  A hypothetical patent directed to a chair with certain elements (e.g., “a back, seat, and four legs”), would cover an accused chair meeting these elements, even if it also included a cup holder and wheels.  However, if the patent specification characterizes the cup holder and wheels as “not” part of the invention, the hypothetical claim would likely be interpreted by a court to preclude embodiments containing these features.

There is simply no reason to state that something is not part of the invention. When such language appears in patents (which I have seen on numerous occasions), accused infringers invariably attempt to convince juries that their accused products practice what the inventors said was “not” part of the invention. If it’s not part of the invention, it should not be discussed in the patent.


While it may be hard to see at first, no one element is “essential” to a patented invention. The novelty of an invention lies in the claim as a whole — i.e., in the claimed combination of all elements collectively.  When features of an invention are described in a neutral manner and not given “essential” or “necessary” status, the breadth of certain claims may be sufficient to capture accused products not containing these features.  This may provide a patent owner with a significant advantage in court.

In contrast, when the patent specification describes features as “essential” or “necessary,” it is very likely that a court would limit the invention to these features and invalidate any claim not reciting them.  Such is especially unfortunate if the inventor later determines that the specification supports claims to broader embodiments not containing these features.

When the patent specification describes features as “essential” or “necessary,” it is very likely that a court would limit the invention to these features and invalidate any claim not reciting them


When it comes to claim drafting, it is important to get it right at the time the application is filed with the Patent Office.  If a claim survives prosecution with no amendments, each element of the claim retains its full range of equivalents – a fancy legal doctrine that allows a claim to be asserted against accused products that are not literally covered by one or more elements of a claim, but close enough to be considered “equivalents.”  However, claim elements that are amended during prosecution will be presumed to lose their range of equivalents.

For this reason, claim amendments (for example, to overcome prior art) should be as narrow as possible and give up only as much scope as necessary to avoid the prior art.  For similar reasons, amendments to “clean up the claims” that are unnecessary to avoid invalidity issues should be avoided.


The primary purpose of the patent specification is to provide written description support and enablement for the patent claims.  While a good background certainly places an invention into context, it almost never supplies written description or enablement for the claims of a patent and, as such, is rarely if ever necessary for patentability. The more you write in this section, the higher the probability that something you write will come back to haunt the patent owner during litigation.

Bryan DeMatteo is the founding member of DeMatteo Law, PLLC — a full service intellectual property and litigation law firm based in New York City.  Mr. DeMatteo and his firm specialize in helping entrepreneurs and small-to-mid sized businesses nationwide grow and succeed by procuring, monetizing and enforcing their intellectual property, as well as protecting their rights in court.

Disclaimer: The content of this article does not constitute legal advice and is provided solely for general informational purposes only. We disclaim any warranties and representations, implicit or express, with respect to the validity of the information in this article or any linked sites. The information in this article is not a substitute for legal advice, and should not be used as a substitute for professional advice. DeMatteo Law is not responsible for any action taken by parties who rely upon the information presented in this article.

← Back to Blog Category: Patent Law
No comments yet.

Leave a Reply