Seventh in a series of articles aimed at scientists, engineers, business managers, non-patent lawyers, and other professionals that desire or need to understand basic principles of patent law and practice. Check out previous editions of this series HERE.

“For the record, I’d like to say that I’m a big fan of forgiveness
as long as I have a chance to get even first.”
-Kinsey Millhone in V is for Vengeance

Sue Grafton’s lovable heroine Kinsey Millhone relentlessly hunts villains on her way to solving murders (and getting even).  While reading patents may not sound as enjoyable as cuddling up with Kinsey, most patents are a would-be private investigator’s dream.

Earlier, we learned that having the right approach to reading patents matters.  In particular, how you read a patent should depend on why you’re reading.  (Check out Basic Patent Law, Part III.)  In brief, when you read for technical information you read a patent differently than if you’re trying to decide whether or not your own invention is patentable or whether your planned process might infringe another’s patent.   To get the most out of your technical reading, pay attention to the “why.”

So how is a patent like a mystery novel?  For discriminating readers, patents provide a bonanza of clues, but it takes effort, and knowing where to look, to unearth the golden nuggets from what’s often a mountain of spectacularly obtuse text.

Our first clues appear on page 1.  The title page of any patent (or published application) offers a wealth of helpful information in a concise package: inventors, assignees, filing date, related applications, art cited by the applicant and patent examiner, classification, and best of all, an abstract that tells us whether or not to even bother with the other 892 columns.

Are you sure you’re looking at a granted patent?  Patent applications automatically publish eighteen months from their earliest filing date, often well before any granted patent issues.  Published international applications are always “just publications”; contrary to popular belief, there is no “world patent.”  Page 1 of a “European Patent Application” seems clear enough, but how does it differ from a “European Patent Specification”?  Only the latter is a granted document.  Here’s a helpful clue: keep an eye on the letter at the end of any patent or publication number: “A” is for (Alibi) a published application, “B” is for (Burglary) a granted patent.

Claims define the property lines or boundaries of a patent.  A good patent detective pays more attention to the independent claims, i.e., claims in a patent that refer to no other claim.  Claims that refer to another claim are more limited in scope by definition.  Claim 1 is always independent.  Why not look there first?  When we apply the magnifying glass, we should detect at least one claim element that could impart novelty even though the rest of the claim may appear conventional.  A-ha!

How can we tell if experiments were performed?  Working examples are often included, but they are not required in a patent.  Look for percent yields, physical properties, and results to identify work actually performed.  Working examples can be written in present or past tense.  In contrast, prophetic or “paper” examples will not be written in past tense and may be a simple recipe for what and how much to combine.

Patent sleuths pay attention to language choices in a patent, i.e., the rhetoric.  What is required by the patent (e.g., “important,” “critical,” “necessary” . . .), and what is merely nice to have (“preferably,” “convenient,” “optionally” . . .)?  “Surprisingly found” usually refers to results that were unexpected and help to establish the non-obviousness (and patentability) of an invention.

The real fun begins when we compare the claim language with other parts of the patent application, especially the “Summary of the Invention” section.  Attorneys usually amend the claims during “prosecution” of the patent application, but the rest of the application is often unchanged.  Consequently, by comparing the language of the independent claims with other parts of the disclosure, we can learn about how claims were narrowed to take into account prior art.

Sometimes, a patentee even teaches us how to avoid infringement.  For instance, suppose claim 1 recites a process using an acid “selected from the group consisting of carbonic, sulfuric, and phosphoric acid.”  Assume the “Summary of the Invention” section also discloses “formic acid” and “acetic acid” in this list, and the examples show how to use all of the acids.  We can infer that formic acid and acetic acid were in the prior art and were therefore carved out of the original claim by amendment.  Consequently, we can “design around” the claim with a blueprint courtesy of the patentee.

To do real patent forensics, however, you’ll want to inspect the “file history,” a record of all documents that passed between the patent applicant and the patent office.  (This is the patent law equivalent of collecting trace evidence or spraying the crime scene with luminol to reveal blood and other bodily fluids.)  Once a mystery, file histories are now available for public inspection after the application has published.  Browse to, and find “PAIR,” the “Patent Application Information Retrieval” system, which has electronic “file wrappers” for published applications and granted patents.  There, you can download documents to understand how prior art was applied, how claims were amended, what arguments the attorney made, and why an examiner finally gave up and allowed the darn claims.  If there’s dirty laundry to be found, the file history is sure to help.

But enough for one day, already–it’s still summer and time to get back to C is for Corpse.  Keep our pointers in mind, and you’ll be well on your way to becoming a patent detective.  Happy hunting!

Stay tuned for Part VIII of our Basic Patent Law series!

– Jon Schuchardt
Check out Jon’s bio page


This article is for informational purposes, is not intended to constitute legal advice, and may be considered advertising under applicable state laws.  The opinions expressed in this article are those of the author only and are not necessarily shared by Dilworth IP, its other attorneys, agents, or staff, or its clients.