The US Patent and Trademark Office recently acknowledged software errors affecting patent term adjustment (PTA) determinations for about 1% of the patents issued from 19 March 2024 to 30 July 2024. For any individual patent, the result could be a shorter or longer patent term than permitted. The errors incorrectly tally the number of days the USPTO delayed examination and the number of PTA overlap days.

The announcement squarely places the burden on patentees to check for PTA errors and to request correction of any found. Because the USPTO cannot or will not identify which of the estimated 125,000 patents were affected, all patentees are advised to verify that their PTA was correctly determined.

Imagine if the US Internal Revenue Service announced that a software bug caused errors in 1% of tax returns and left it up to individual taxpayers to recalculate their returns to determine if theirs was in the 1%?

The PTA value displayed on a patent places the public and competitors on notice as to when the patent's limited monopoly will expire. Understandably, patentees are motivated to identify and correct PTA errors that shorten patent terms. Patent attorneys generally risk charges of inadequate duty of disclosure and inventors risk unenforceable patents if they fail to act to correct known prosecution errors. However, since the USPTO does not require patentees to check for PTA errors, no one expects patentees to identify all of the errors, including those that incorrectly extend the patent term.

If the estimated 1,250 patentees affected by this software error seek PTA correction, the USPTO requires requests to be filed within seven months of the patent's issue date. For patents which issued 19 May 2024, the final date to request correction is 19 October 2024.

The formula to calculate PTA involves a straightforward summation of various USPTO delays (termed Types A, B and C), minus applicant and overlap delays:

The devil is in the details. The iterative nature of examination creates many windows with unique start and stop dates to tally and categorise as examiner or applicant delays. Applicant delay, involving assessment of 14-plus types of actions, is further complicated by imprecise filing deadlines that can land on weekends, holidays or other days when the USPTO closes for emergencies or IT shutdowns.

Type A delay occurs when the USPTO fails to respond within the timeframe specified. USPTO data shown in Table 1 indicates compliance with certain PTA windows is lacking.

With this poor compliance, it's no wonder that 63% of all patents receive some PTA, with 25% of patents obtaining PTA extensions for more than a year. Currently, 32% of the applications are first examined within 14 months - down from 42% in May 2023 - meaning for future patents, we should expect to see even more excess patent term.

Determining the amount of PTA involves exactly the sort of calculation that computer software was designed to perform: a series of rule-based steps resulting in a specific numerical outcome. While there are some nuances to PTA calculation, it is significantly simpler than complying with the US tax code. Millions confidently rely on commercial software to accurately calculate their tax returns.

Yet, this is not the first time the USPTO has systemically miscalculated PTA.

In April 2022, patent litigator Dinis Cheian identified two separate software mistakes that mis-awarded up to 90 days excess patent term in over 27,000 patents. A follow-on July 2024 study identified eight drug patents with erroneously granted PTA which, if left uncorrected or unchallenged, would result in extended term and delayed generic accessibility. One example is shown in Figure 1. The 107 excess days are estimated to yield up to $514.8 million of excess revenue for Gilead Sciences Inc. This would incorrectly inform generics competitors about when a key patent covering the drug Genvoya would expire.

Figure 1: Example of drug patent with extended PTA

In September 2024, the Senate Judiciary Committee sent the USPTO a letter demanding explanations and action to correct erroneous PTA determinations, including those for drug patents identified in the July 2024 study.

While waiting for the USPTO's response, the Senate may want to consult the 2021 OIG report on PTA, which found that

• 8% of the PTA software requirements were not fully compliant with relevant statutes, regulations and caselaw;
• 7% of the awarded PTA could not be verified; and
• About half of the 1,055 sampled patents had at least one PTA calculation that could not be verified.

The OIG recommended, among other things, that the USPTO update its document descriptions to help improve the accuracy of its PTA calculations. So far, only one document description - out of the nearly 400 in use - has been updated.

The USPTO's legacy computer system was not originally designed to calculate PTA. Moreover, PTA legal framework is unsettled, with at least eight court decisions affecting the formula for calculating and awarding PTA since 2010. These rulings have not been consistently incorporated into the PTA calculating software. In 2021, the OIG found that "since the last updates to the [PTA] system requirement were done in 2015, the backlog of requirements has been growing. The USPTO considered updates to the PTA calculator but has not implemented them due to competing IT funding priorities".

Further, a 2020 OIG oversight report faults the USPTO for not adequately vetting the software development contractors who would likely update the PTA calculator.

It is unclear what, if anything, the agency has done to upgrade its IT system so that it complies with PTA regulations.

When Cheian filed a FOIA request to obtain the PTA software code, with the hopes of helping the agency debug the programme, his request was denied on the grounds of withholding records for information "compiled for law enforcement purposes" to "prevent future illegal acts".

Meanwhile, these ongoing systemic shortcomings have resulted in an untold number of patents containing erroneous PTA adjustments. Ironically, the latest PTA software errors were attributed to a system update.

The cost of checking for and requesting correction of the USPTO-generated PTA errors will have its largest impact on resource-challenged inventors who are least able to afford it. Large companies are more adept at responding to complex procedural requirements. In fact, data obtained from Petition.ai (the author is an advisor for the company) indicates that Google files the most requests to correct PTA and has the highest grant rate of 95.5%, compared to a 73% average.

The senators suggest that the patent office should manually check PTA awarded to all FDA-listed drugs.

But as Professor Sean Tu, from West Virginia University College of Law, points out, "we can all agree that no one should get extra patent term because of a computer error".

All patent applications should be similarly processed according to current statutes and rules, regardless of technology, applicant entity status or inventive impact. If computer software can be developed to implement the US tax code accurately, surely America's innovation agency can irradicate software bugs in their PTA calculator. Moreover, the USPTO is authorised to sua sponte issue, without charge, certificates to correct patents containing office-generated errors. Congress should require the patent office to identify and fix mistaken PTA awards in this manner.

Sean Tu, professor at West Virginia College of Law, and patent litigator Dinis Cheian contributed to this article but it does not reflect their organisations and clients’ statements or views.