Not All Prior Art Is Created Equal

By John Sullivan*

Patents are presumed to be valid once issued by the patent office.” In recent years, this statement has become debatable as more and more patents are found invalid by district courts or by the “death squad for patents” — the Patent Trial and Appeal Board (PTAB) — a division of the USPTO, the very same organization that originally issued the patents.  Effective use of invalidity defenses such as prior use is winning many litigations and dramatically lowering licensing fees and patent values.

Patentable subject matter (35 U.S.C. §101) is an extremely popular ground for arguing invalidity following the Alice decision at the Supreme Court in 2014. This tends to be a purely legal argument focusing on whether an invention is an abstract idea that fails to claim significantly more than the abstract idea itself.

Obviousness is another well used ground for invalidity (35 U.S.C. §103) made much more popular at the Supreme Court by virtue of a 2007 decision, KSR International Co. v. Teleflex Inc.  Obviousness can be supported by prior use which may provide all or part of a defense that builds on combinations of multiple pieces of art post KSR.

Prior Art and District Courts

Prior art/prior use is also a traditional ground for invalidity (35 U.S.C. §102).  Under section 102(1) (conditions for patentability; novelty), “A person shall be entitled to a patent unless the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention.” [Emphasis supplied.]

Searching for grounds for invalidity requires evidence that predates the target patent.  Most printed publications such as technical papers include publishing dates making them straightforward to date.  Unfortunately, a patent or a technical publication will frequently not include all the key elements of the claim that you want to invalidate.  More data is required.  A product that could be useful as prior art (or prior use) can be analyzed by reverse engineering the device to show the presence of all the claim elements of a patent that one wants to invalidate. Determining the date of public use or sale is however often much more challenging especially in the semiconductor or electronics space where clear manufacturing or design dates usually do not exist.

To start a prior use search, a traditional publication search can produce indications of use and identify devices and products that have a high probability of incorporating the technology claimed in the target patent.  Next step, a review of available analysis.  The extensive TechInsights/Chipworks library of analysis that stretches back more than 25 years is the world’s  premier public source used to look for more evidence showing the asserted patent claims on devices manufactured before the priority date of the asserted patent. In fact, with a little digging into historical corporate assets this library even has content that goes back to 1964. If no existing report on a given device is available, it is common to commission the reverse engineering of a vintage product for the express purpose of showing prior use.

Many of the results of past reverse engineering projects take the form of a technical report that has been made available for purchase by the general public. Once created this technical report is a publicly available printed publication. These printed publications can then be used during a trial as part of an invalidity defense. The date that the reverse engineering report was created is not an issue in district court. The more important point is that the report describes a publicly available product that predates the priority date of the patent in question.

Prior Art and the PTAB

Now consider Inter Partes Reviews at the PTAB. An IPR is a procedure that was created as a result of the America Invents Act signed by President Obama on September 16, 2011. It replaced the Inter Partes Re-Examination procedure as a means to challenge an issued patent. IPRs often take place concurrently with a district court action. In fact, an analysis of 3 years of PTAB statistics found that 80 percent of IPR filings are co-pending with federal court litigation.

Under 35 U.S.C. §311(b), “A petitioner in an inter partes review may request to cancel as unpatentable one or more claims of a patent only on a ground that could be raised under section 102 or 103 and only on the basis of prior art consisting of patents or printed publications.”   The act specifies only patents or printed publications. This is the very important distinction defining the prior art that can be used in a litigation versus an IPR.  Prior use may be off the table unless certain conditions are met. This evidentiary restriction in IPRs is based on the need for judicial economy, i.e. streamlining evidence such that cases can be simple and can be resolved within the 12 month statutory limit.  That doesn’t necessarily preclude prior use, it just limits acceptable examples of prior use to that which is translated into a printed publication.

Arguably, if a publicly available report exists that describes the prior use product it will be accepted by the PTAB.  If this report was created before the priority date of the patent the PTAB will accept the report itself as prior art evidence and the earlier still date of the device under analysis is moot. Reverse engineering reports are printed publications. Given that it is established that they were created before the priority date of the patent, they can be considered valid prior art in an IPR. The use of a reverse engineering report in an IPR now becomes an exercise in proving that the report was publicly available prior to the patent priority date.

The threshold for acceptability of publicly available is somewhat fuzzy, see L-3 Communication Holdings Inc, et al. v. Power Survey LLC and GlobalFoundries U.S. Inc. et al. v. Zond LLC.  In L-3, an internal Sarnoff report was held to be inadmissible as not publicly available since its distribution was limited while in Global Foundries an obscure Russian doctoral thesis was held to be publicly available through its registration at the Russian State Library making it available to all (in particular those who can read Russian).

Provided there is significant documentation showing public availability and its publication date, there is little to lose from submitting a report.  The evidence will be looked at by the PTAB, which has a history of narrowly excluding evidence and only when petitioned by the patent owner.  Regardless, the PTAB will have seen the evidence. Whether or not they rely on it for a final decision it may still affect the result. In the instance where evidence is excluded or not convincing to the PTAB, the prior use evidence is not estopped (see Star Envirotech Inc. v. Redline Detection) as the evidence from an actual machine or device is specifically excluded from the PTAB and cannot be considered as printed publication evidence that was or could have been produced in the IPR.

Defense teams may file IPR petitions to the PTAB by supplying prior art evidence in the form of technical reports from companies like TechInsights. To prove that these reports are valid pieces of prior art that can be used in an IPR, companies can provide a “printed publication” document, which will help to establish when a device that is the subject of a reverse engineering report was created. The creation date of the report may be sufficient if the report contains the following:

  • snapshots from internal report databases that track when a report was completed
  • screen shots from web pages that advertise the report and when it will be available
  • records of any email communications that went out to announce the report
  • report sales dates
  • declarations that attest to the completion date of the report, which ideally are created by the author of the report or by a chosen representative

Prior use evidence is a rich source of invalidation arguments for patents.  Savvy defense counsel have long used prior use investigations to decisively end district court litigations.  Prior use evidence is proscribed by the statute in IPR procedures at the PTAB. But, with diligent use of engineering reports and other obscure but publicly available printed publications patents of questionable novelty can be effectively neutralized early in a litigation cycle.


*The author, John Sullivan, is a patent and technology specialist at TechInsights, a global leader in patent services. The company’s library of analysis stretching back more than 25 years is a premier public source for evidence showing asserted claims on devices manufactured before the priority date of an asserted patent.

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