Detectability: Looking Beyond the Legal Requirements for Patent Grant to the Practical Requirements for Future Enforcement of the Granted Patent

14 Aug 2025

Oscilloscope Displaying Voltage Signal Captured from Exposed Test Point of Printed Circuit Board

A potentially overlooked aspect in the preparation of patent applications is a focus on the detectability of the claimed invention. The term ‘detectability’, as used in this article, is the ability to prove infringement of a patent’s claims solely from the experimental analysis of an alleged infringer’s products.
 
Unlike novelty and inventive step, detectability is not a legal requirement for obtaining a patent. But, as a practical matter, detectability of infringement by an alleged infringer product is necessary for enforcement of any patent. Patents are the right to exclude others from the use of the patented invention. Regardless of whether this right to exclude is enforced through negotiations or a formal lawsuit, an initial step is the collection of objective infringement evidence.
 
For some technologies, detection of infringement is straightforward. Use of a claimed mechanical invention is generally the simplest infringement evidence to detect. The evidence of infringement can often consist of just pictures and measurements of the disassembled alleged infringer product. However, for many technology areas such as software, detection of infringement can be more challenging. Other than products linked to open-source software, the source code of an alleged infringer’s software product is rarely available. Alleged infringer marketing material also typically only details the benefits or functional results of a software product. Further, many software products are implemented as a cloud-based service, with the software operating on servers in locked data centres.
 
Acquiring an initial prima facie case of infringement therefore presents a bottleneck for enforcement of many patents. As a granted patent’s claim language can be difficult to change, the best time to address the detectability issue is during the patent drafting process. Patent claims with undetectable technical elements educate competitors on previously secret product details, without conferring the benefit of a practical patent enforcement route. Companies with larger research efforts can first prioritise patenting those inventions that are more easily detectable. Less easily detected inventions can then be intentionally maintained as a trade secret. Trade secrets, unlike patents, have a potentially eternal lifespan and do not require additional patent office or professional fees to maintain.
 
Legal Limitations on Access to Infringement Evidence
 
Confidential information of an alleged infringer also cannot be relied on to prove infringement. In most patent jurisdictions, discovery of confidential technical details from the alleged infringer is simply not available or is severely limited. And, even if limited discovery is permitted, the court will impose an initial threshold of infringement proof for the patent owner to overcome before allowing targeted discovery.
 
In Singapore, the patent owner normally shoulders the burden of proof for the determination of patent infringement. Section 68 of the Patents Act, however, shifts this burden of proof to the alleged infringer if the alleged infringer’s product is “new or a substantial likelihood exists that the product is made by the process and the proprietor of the patent has been unable through reasonable efforts to determine the process actually used.” However, “the court is not to require the [allegedly infringing] party to disclose any manufacturing or commercial secret if it appears to the court that it would be unreasonable to do so.”
 
The United States District Courts permit broad-scope discovery of confidential material during a patent lawsuit. However, the pleadings for any such patent lawsuit require the filing party’s attorneys to attest under the Federal Rules of Civil Procedure Rule 11 that the infringement contentions within a lawsuit filing “have evidentiary support or . . . will likely have evidentiary support after a reasonable opportunity for further investigation or discovery”. Sanctions for non-compliance with Rule 11 “may include nonmonetary directives; an order to pay a penalty into court; or . . . part or all of the reasonable attorney's fees and other expenses directly resulting from the violation.” Hence, U.S. legal counsel will demand extensive objective evidence of infringement from their patent owning clients prior to filing any patent lawsuit on their behalf.
 
Further, in many jurisdictions, allegations of infringement that prove to be unfounded can result in civil damages. The Singapore Patents Act, for instance, provides that a party ‘aggrieved’ by false allegations of patent infringement can commence proceedings against the patent owner for ‘groundless threat’. In this proceeding, the patent owner bears the burden to prove that their allegations of infringement against the aggrieved party are justified. The U.S. courts have a somewhat similar legal proceeding, called ‘declaratory judgement’, that aggrieved parties can pursue against patent owners alleging infringement.
 
Experimental Analysis Methodologies
 
Inventors within a field of art are typically well-aware of the available experimental analysis methodologies, their related tools, and their capabilities for the field of art. Larger technology companies often have dedicated staff (or access to outside vendors) that specialise in experimental analysis of intermediate or finished products. Published research papers in each field of art often include charts and other data obtained from the available experimental analysis tools and methodologies along with the conditions or parameters employed during such experimental analysis. The dedicated staff or outside vendors often perform work for company departments called ‘Quality Assurance’, ‘Competitive Analysis’, ‘Forensic Analysis’, ‘Failure Analysis’, or ‘Research’.
 
Example experimental analysis methodologies for consumer electronics include the following:

• PCB. Electrical devices often include at least one printed circuit board (PCB) with exposed ‘test points’ that allow technicians or automated test equipment to connect probes for testing and debugging the PCB's circuitry. These test points can be electrically connected in parallel to an oscilloscope (or to a sniffer tool) to monitor the operation of the electrical device. Such testing can be simplified by the presence of generic off-the-shelf integrated circuits on the PCB that can be cross-referenced to published datasheets.

• Software. If source code or other written documents is not available for the workings of the software (or firmware), detection of infringement can possibly be obtained from: (i) a sniffer tool that intercepts data as it is transmitted over a data bus or network; (ii) a test script that inputs various data and instructions to the alleged infringer’s software and then monitors outputs from the software; or (iii) expert review of data logs or other files exported by the software during its normal usage.

• Industry Standards. Evidence of infringement of patent claims covering published industry standards can be demonstrated using the same methodologies employed to detect use of software as the execution of these standards is primarily driven by software (or firmware). These methodologies are aided by the detailed specifications published by the industry standard organisations. The prominent industry standard organisations for consumer electronics include 3GPP, ANSI, Bluetooth SIG, ETSI, IEEE, INCITS, ITU, JEDEC, and USB-IF.

• Materials. Detailed analysis of an integrated circuit’s internal design is typically a more detailed and expensive endeavour. The minute dimensions of individual cells within the integrated circuit can often only be detailed with use of Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), or Atomic Force Microscopy (AFM). If the patent claims refer to specific metals, Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) can be used for surface composition analysis. Crystallography techniques, such as X-ray diffraction, can be used to detail the structure and properties of crystalline structures.

 
Patent Figures Incorporating Detectable Data
 
Basic knowledge of the available experimental analysis methodologies can be extremely helpful for a patent agent’s drafting of a patent application. When drafting patent applications, not all of the prior art is known. Examiners often locate prior art of which the inventor and patent agent were unaware. The available experimental analysis methodologies, in comparison, are generally well known at the time of the patent drafting and will still exist when efforts to enforce the patent against third-parties are made in the future.
 
When preparing the patent application, the patent agent can consult with the inventors regarding the available detection techniques and assemble experimental data within charts or figures for the patent specification. Typically, the inventor’s experimental data which is available at the time of patent application drafting will closely match the infringement analysis data of an alleged infringer’s product purchased on the open market years later.
 
Knowledge of the available experimental analysis methodologies can also guide the patent agent toward an optimised structure during patent application drafting, many years before the patent claims are ever enforced. During a review of the available methodologies, it tends to be apparent that some aspects of the invention may not be easily detectable, while other aspects may be easily detected by the known experimental analysis methodologies. With this knowledge, claims can be drafted to prioritise those technical aspects of the invention that are easily detected. As an example, the patent agent may observe that the invention relies on specific electrical signals that could be observed by an oscilloscope, and therefore draft claims tailored to the operation of those signals.
 
If infringement data is likely to be collated from an oscilloscope, then a figure of the patent application should ideally illustrate how such signal data would appear on an oscilloscope screen. If the infringement data is from a specific spectrometer device, then ideally the patent application should include a figure illustrating how use of the patent would appear on the output from the spectrometer device. Similarly, typical output report formats for text scripts or sniffer tools can be employed to illustrate usage of the claimed invention.
 
If the likely evidence of infringement would be a published specification of an industry standard, it is helpful for the vocabulary employed in the specification to follow the nomenclature common to previous versions of the industry standard specification. Additionally, typical formatting of timing diagrams and other content of the previous industry standard specifications can be mimicked within the new patent application’s figures and charts. For instance, the figures in the new patent applications can employ the same chart axis labels, data parameters, opcode bit format, and data packet format conventions found in previous industry standard specifications.
 
If the likely evidence of infringement would require use of advanced material science analysis equipment (such as SEM, TEM, AFM, ToF-SIMS, and X-ray diffraction) to create, it is helpful for the patent agent to be aware of the limitations of this equipment when drafting the claims. Manufacturing process claims in particular can be difficult to prove from a final product. Hence, a key challenge in drafting the claims of a manufacturing method will be identifying which aspects of the manufacturing process leave behind residual evidence in the final product. A careful evaluation may lead to the conclusion that certain aspects of the manufacturing process are better kept as a trade secret if they represent an interim step that leaves behind no evidence of its use within the publicly available final product.
 
Mechanical invention claims are the easiest claims to match up to expected experimental analysis data (such as pictures and measurements of the disassembled infringing product). Simplified CAD-style drawings of the invented mechanical part in the invention disclosure are usually most helpful for bolstering the claim charts needed for future enforcement efforts. These drawings ideally should match up to the anticipated top, side, and perspective view of an alleged infringer’s design. Extraneous details of the patent applicant’s design, such as details not specifically claimed and/or discussed in detail in the text of the patent application, should be removed from the figures. As patents are only a right to exclude others, the figures should anticipate the main features of an alleged infringer rather than attempt to represent the specific engineering choices of the inventor’s prototype design.
 
These types of figures for the patent application can generally be prepared from the research material and experimental data assembled by the inventor during the initial development and potential testing of the invention’s prototype.
 
Detectability Data as Checklist for ‘Picture Claims’
 
Regardless of the technology area, the figures of the patent owner’s experimental analysis data can be used as a checklist to prepare ‘picture claims’ of the invention. In this manner, future endeavours to enforce the patent have a clear path to provide evidence of the use of each claim element in the alleged infringer’s product. Ideally, during the drafting process the patent agent can visualise a future claim chart presented during negotiation or court enforcement proceedings where each claim element is matched up with experimental data obtained from the alleged infringing product.
 
Including such data in the patent application increases the credibility of the patent owner during negotiations or litigation enforcing the patent. Claim charts exchanged with the alleged infringer or court can, for instance, present each claim element side-by-side with the coinciding patent figures and infringement analysis data of the alleged infringer’s product. This visual comparison provides a clear infringement story to the business and legal staff of alleged infringer as well as potential judges or juries evaluating the patent owner’s infringement assertion. This type of presentation carries significant weight during negotiation or litigation because the experimental analysis results are objective and repeatable by the alleged infringer or court.
 
Detectability vs. Efficacy
 
It should be noted that the detectability of an invention is different from the efficacy of an invention. Detectable experimental data potentially demonstrates that an alleged infringer’s product does not have an alternative non-infringing design and infringes the patent’s claims. Efficacy data, on the other hand, does not necessarily prove infringement by an alleged infringer’s product. It is possible that the documented positive results for a claimed invention are also available from an alternative non-infringing design. Efficacy data is valuable during prosecution of a patent application to establish that the claimed invention possesses inventive step because its efficacy data demonstrates that the claimed invention provides unexpected positive results.
 
A patent specification, therefore, should preferably include sample data demonstrating efficacy of the claimed invention (to help obtain a patent during prosecution of the patent application) and also include sample data illustrating the claimed invention’s detectable characteristics (to help enforce the patent after grant). Unlike prior art, most of which is unknown, detectability aspects of an invention are well-known at the time of patent application drafting and are also largely static over the lifespan of the granted patent. Each patent specification, therefore, can be drafted with a clear idea of what would be required to prove future infringement for the claimed invention.
 

- Written by Patrick W. Duncan, Patent Agent, Drew & Napier