Duplicative petitions are malicious---coordinated attacks towards patents is extremely easy absent negative consequences.

Similar to the previous findings, there were unintended consequences of the open standing requirement for bringing an IPR petition. Because of the open standing requirement that any third party can petition to invalidate any claim of a patent, there are many ways a patent can get challenged. As illustrated in Figure 2 below, a single petitioner can file separate IPR petitions against different claims within a single patent, multiple petitioners can file separate petitions against a single claim of a patent, and a single petitioner can keep filing multiple petitions against a single patent claim. As a result, the USPTO has been criticized for giving challengers too many "bite[s] at the apple" when any third party could inundate patent owners with multiple IPR proceedings. 8 1

[Table Omitted]

As a potential result (or at least a perception) of an overcorrection, serial IPR petitions have become petitioners' secret weapon against patent owners and a thorn in the side of the USPTO. Serial IPR petitions occurs when there are multiple petitions to invalidate the same patent.

According to USPTO's own special report, only around 15% of the patents with an IPR face two or more petitions. 82 16% of multiple petitions are still filed after the PTAB institutes the first IPR.83 Additional research in 2017 found that on a per patent basis, 24% of the patents were challenged more than once.84 In the same study, there also appears to be instances in which the PTAB admitted prior art references in subsequent petitions after previously denying the very same prior art in an earlier petition.85 Another Berkeley study concluded that "about 30% of challenged patents are subject to more than one IPR petition" based on data until 2018.86 None of the studies mentioned above has the granularity of serial petition problems per industry. This Note attempts to bring more data in to inform the extent of the serial petition problem broken down by industry.

For the purposes of this analysis, a serial IPR petition is defined as an IPR petition that challenges the same patent that is also the subject of another petition. Note that this is a broad defmition; multiple petitioners can challenge claims of the same patent. Out of all 11,909 petitions filed between January 1, 2013, and September 23, 2020, there are 7,074 unique patents, which means that the remaining 4,835 petitions are repeat challenges of the 7,074 patents. Put another way, 41% of the time, PTAB looks at a petition they have already seen of the patent being challenged some other way, either by the same or different petitioners. 87

[Table Omitted]

On a per patent basis, shown above in Table 4, out of all of the patents ever challenged in IPR proceedings, 32% of the patents were challenged more than once, either by the same or different petitioners. Similarly, companies, large and small, seem to face extensive serial attacks on their patent portfolios. These follow-on petitions usually assert new or modified arguments to challenge the same patent claims. Theoretically, the PTAB could and should deny institution if there are multiple petitions. The AIA also expressly authorizes the Director to deny institution if the petition presents "the same or substantially the same prior art or arguments previously ... presented to the Office." 88 Indeed, the PTAB adopted the precedential decision of General Plastic Industrial Co. v. Canon Kabushiki Kaisha89 in 2017 and designated seven factors for determining whether to reject follow-on petitions in an attempt to curtail the serial petitions problem. However, it is unclear whether such decision carries any actual weight.90

As such, the open standing requirement allows a petitioner or multiple petitioners to coordinate an attack against a patent owner or a patent portfolio without any negative consequences. Patent owners often find themselves on the receiving end of an onslaught of IPR petitions, each of which will cost at least thousands of dollars to defend while the challenged patents would be tied up in the PTAB for potentially eighteen months. 9 1 Well-funded companies have been especially liberal with such practices, using the PTAB as a favored jurisdiction to safeguard their patent portfolios. They could, in theory-and, in fact, have-submit requests to invalidate the same patent against a smaller startup, tying up its entire patent portfolio at the PTAB with little chance for the startup to countersue at the district court level.