Search for a command to run...
Peer review represents a cornerstone of scientific and scholarly publishing. Despite many unanswered questions about the value of peer review (Tennant and Ross-Hellauer 2020), it is widely assumed that peer review improves the quality of published articles. In turn, reviewers accept peer review requests based on the interest and relevance of manuscripts, and as a service to their fields (Severin and Chataway 2021). It has been estimated that reviewers contributed over 100 million hours towards peer review in 2020, with an approximate collective value of over USD 2 billion (Aczel et al. 2021). Millions of peer reviewers participate in peer review every year (Aczel et al. 2021) through invitations from the many thousands of editors who support peer reviewed journals. Peer review occurs through a stepwise process (Figure 1), where manuscripts are first considered by editors, with a subset of manuscripts progressing to external peer review. These stages involve different individuals with often differing expertise and hence capacities to assess research quality. Peer review has, however, paid less attention to detecting manuscripts with questionable integrity. This could reflect assumptions that relatively few manuscripts present integrity issues, and that peer reviewers may be poorly equipped to detect integrity issues within manuscripts (Stroebe et al. 2012). The rise in manuscripts from paper mills (Behl 2021; Bricker-Anthony and Giangrande 2022; Cooper and Han 2021; Heck et al. 2021; Pinna et al. 2020; Van Noorden 2023) and the possible misapplication of large language models (LLM's) to generate and scale fast-churn manuscripts (Grimaldi and Ehrler 2023; Suchak et al. 2025) highlight the need to revisit assumptions about the capacity of peer review to detect unethical or low-value submissions. Suspected submissions from paper mills have now been described by many biomedical journals (Behl 2021; Bricker-Anthony and Giangrande 2022; Cooper and Han 2021; Heck et al. 2021; Pinna et al. 2020; Seifert 2021). Other journals have described receiving large numbers of repetitive manuscripts (Jin 2022), suggesting the possible misapplication of LLM's by paper mills or individual teams (Mainous III 2025; Munafò et al. 2024; Stewart 2025). Such changing patterns of submissions (Mainous III 2025) and, in some cases, publications (Stender et al. 2024; Suchak et al. 2025) question assumptions that unethical manuscript submissions are infrequent. As submissions from paper mills and the use of LLM's to produce derivative manuscripts become more frequent, the awareness of scaled and repetitive submissions is also expected to grow (Byrne and Stender 2025). This awareness can be leveraged through peer review processes that actively consider research and scholarly integrity in addition to quality (Abalkina et al. 2025). There are further reasons to focus on peer review to counter submissions from paper mills. In contrast to genuine research, where the rate-limiting step towards publication is likely to be conducting the research, the rate-limiting step for paper mills is likely to be peer review (Byrne et al. 2022). It is, therefore, not surprising that paper mills attempt to manipulate this rate-limiting step (Byrne et al. 2022; Matusz et al. 2025), for example, by recruiting editors and peer reviewers to facilitate manuscript acceptance (Abalkina et al. 2025; Joelving and Retraction Watch 2024; Pinna et al. 2020), and by creating fake reviewer identities (Matusz et al. 2025). Given the critical and rate-limiting importance of peer review to paper mills, their manuscripts and submission tactics are likely to continually evolve to evade detection (Byrne et al. 2024), highlighting the need for peer review processes to keep pace (Abalkina et al. 2025). The scale and changing nature of the paper mill problem highlights the value of rethinking peer review according to the Swiss Cheese Model of error and accident causation and prevention (Larouzee and Le Coze 2020; Wiegmann et al. 2022). The Swiss Cheese Model represents processes as different slices of cheese, where strengths are represented by the cheese, and weaknesses or failings are represented by holes in the cheese (Figure 1). The Swiss Cheese Model proposes that errors or accidents can occur when blind spots at different process stages are shared, and that errors and accidents can be prevented when processes have complementary areas of strength (Wiegmann et al. 2022) (Figure 1). When applied to peer review, the Swiss Cheese Model allows each stage of the peer review process to be recognised as a new opportunity to detect problematic manuscripts (Figure 1). Ideally, most problematic submissions will be detected at the early stages of peer review, with fewer problematic submissions progressing to the later, more resource-intensive stages (Figure 1). Nonetheless, if problematic manuscript features can be communicated back to editors, this can tighten some ‘holes’ through which problematic manuscripts could otherwise slip. While no peer review system can successfully detect all submissions from bad actors (Cooke et al. 2024; Wykes and Parkinson 2023), continuous, real-time improvements could reduce the numbers of accepted manuscripts that, with the benefit of hindsight, should have been rejected. Other authors have recently described the features of paper mill manuscripts that can be detected by editors and peer reviewers, and how the peer review system can better respond (Abalkina et al. 2025; Christopher 2021). We will largely not repeat previous advice but instead focus on opportunities that have not been previously discussed. In all cases, we will describe simple modifications of existing practices that could be easily implemented (Table 1). We will give some final considerations to the possible consequences of implementing these recommended changes at scale, and how some publisher and journal practices might need to adapt as a result. Allow reviewers to explain why invitations are declined: Offer informative reasons for declining invitations. Allow multiple reasons to be selected. Allow free text comments. Separate free text comments from peer reviewer suggestions. Ask peer reviewers to describe integrity concerns through neutrally worded questions to reviewers and confidential comments to the editor. Where reviewers describe integrity concerns remove requirements to return comments to authors and require descriptions of concerns through confidential comments to the editor. Editors make final decisions as to whether manuscripts will be accepted or rejected; therefore, they play critical roles in peer review (Sever 2023; Tennant, and Ross-Hellauer 2020). Many journals have editorial assistants or in-house teams checking submissions and making decisions on initial desk rejections (Horbach and Halffman 2020). These early decisions determine whether and how manuscripts progress to the later stages of peer review, and how much time and other resources will be assigned to individual manuscripts. It is in both editors' and peer reviewers' interests that editorial review identifies low-value and potentially dishonest submissions as effectively as possible to reduce the resources that could otherwise be wasted through further consideration (Cooke et al. 2024; Sever 2023; Wykes and Parkinson 2023). To detect problematic submissions at the editorial review stage, publishers and journals are increasingly investing in research integrity teams, manuscript screening tools and using known features of problematic submissions to highlight manuscripts for desk rejection (Abalkina et al. 2025; Alam and Wilson 2023). However, despite the best efforts of journals and publishers, not all problematic submissions will be detected through editorial review (Behl 2021; Bricker-Anthony and Giangrande 2022) (Figure 1). First, screening tools may not be available to all journals, particularly where individual journals need to pay for access. Second, most screening tools represent commercial products where the targeted features may not be disclosed, and practical understanding of the output could be limited. This could lead to uncertainties over the value of predictions and the decisions that editorial staff should take in response. Third, in-house teams and screening tools are unlikely to recognise all paper mill or mass-produced manuscript features, given our currently limited knowledge of the extent of the paper mill problem, and the predicted capacity of paper mill submissions to evolve in response to improved detection (Byrne et al. 2024). Finally, awareness of problematic submissions is likely to vary between individual editors and journals. For example, some editors might simply be unaware of paper mills or assume that their journal will not be targeted. Similarly, editors might not recognise features of problematic submissions, particularly if their journal has not been previously (or knowingly) targeted or receives few submissions. Editors need access to reliable and up-to-date information on which to base editorial decisions. There is a clear need for scaled education of editors and peer reviewers, so they are aware of paper mills, their current submission tactics and emerging features of problematic manuscripts (Abalkina et al. 2025; Benyó et al. 2024; Wittau and Seifert 2024). Education and screening tools need to be widely available, particularly to smaller, less well-resourced journals that could otherwise become easy targets. Once editors, assistants and journal teams are aware of paper mills, they can gather their own intelligence, for example by monitoring submission trends to flag new topics that could be exploited by paper mills (Mainous III 2025). As we will describe below, allowing peer reviewers to express integrity concerns at different stages of the peer review process can allow other features of problematic submissions to be recognised and potentially acted on (Figure 1). If a manuscript is not desk-rejected, editors will invite experts to review the manuscript, with the aim of securing 2–3 reviewers as quickly as possible (Sever 2023). While the process of inviting reviewers might not always be viewed as a separate stage of peer review, many journals are likely to be spending more time and resources issuing peer reviewer invitations, as more invitations are declined (Chataway and Severin 2021; Fox et al. 2017; Sever 2023). Difficulties in identifying peer reviewers could be exacerbated through a growing reluctance to approach author-suggested reviewers, in case these individuals are linked to paper mills (Wittau and Seifert 2024). Given the value that paper mills are likely to place on manipulating peer review, editors should use trust markers when electing peer reviewers, particularly where reviewers are suggested by authors (Abalkina et al. 2025). A widely recognised trust marker is the use of institutional email addresses by authors (Seifert 2021; Stewart 2025), and by extension, nominated peer reviewers. Nonetheless, close attention should be paid to institutional email addresses (Abalkina et al. 2025), as these can be configured to resemble genuine addresses while containing minor yet critical differences. While declined peer review invitations are generally not welcomed by editors, declined invitations provide opportunities to delay or prevent acceptance of problematic submissions. After many invitation refusals, some editors may feel obliged to continue to approach reviewers with increasingly tangential expertise (Sever 2023). Rather than continuing to invite reviewers who may be poorly equipped to assess research quality or integrity, journals could require desk-rejections for manuscripts that fail to secure reviewers after a defined number of invitations (Table 1). Declined review invitations also provide scaled opportunities to obtain feedback from reviewers. Some reviewers can recognise low value submissions from information supplied through peer review invitations (Severin and Chataway 2021; Stender et al. 2024). However, journals typically offer only generic reasons to decline peer review invitations, such as lack of time or expertise (Tite and Schroter 2007; Willis 2016) and can sometimes allow just one response or reason to be selected. Generic responses might not capture the reason(s) why invitations are declined, particularly if reviewers have specific concerns. Offering a broader range of responses (Figure 2), such as ‘manuscript possibly out of scope’, or ‘manuscript of possibly limited value’, and allowing the selection more than one response, could provide more informative feedback, with little extra effort from reviewers. Allowing reviewers to explain why they decline review invitations could also generate a better understanding of why increasing numbers of peer review invitations are declined (Tennant, and Ross-Hellauer 2020). Another simple approach to gain feedback is to provide text boxes to allow invited reviewers to explain why they are declining review invitations (Figure 2). Free text responses can also be offered to capture details of alternative reviewers. However, researchers who decline to review manuscripts due to integrity concerns seem unlikely to recommend these manuscripts to others. Text boxes for comments should therefore ideally be separated from text boxes for capturing reviewer suggestions. In cases where researchers do not suggest alternative reviewers, they should have the option of explaining why, such as advising that the manuscript should not be sent for peer review. Once a reviewer has accepted a peer review request, they will usually supply their review through the journal's editorial platform. This involves providing comments to authors, optional confidential comments to the editor, and answering a range of questions about the manuscript and themselves as reviewers (Dine et al. 2015). It has been proposed that if reviewers were asked about integrity concerns, they might be more likely to consider this possibility (Stroebe et al. 2012). Journals should therefore include at least one compulsory reviewer question on this topic (Table 1). This approach could be particularly important in the case of less experienced peer reviewers, who might be more reluctant to express integrity concerns. Reviewer questions on manuscript integrity should be carefully and neutrally worded. Editors could also request reviewers to scrutinise items or sections of a manuscript without mentioning any specific concerns that they may have. With many existing expectations of peer reviewers, adding further questions could add to reviewer fatigue and reduced compliance. The addition of new administrative requirements should ideally lead to the removal of others (Stein 2015). For example, most review platforms require peer reviewers to provide comments to authors. This is a reasonable requirement for manuscripts that are submitted in good faith. However, in the case of paper mill submissions, this requirement could result in peer reviewers suggesting valuable improvements that paper mills could easily implement and then carry forward to future manuscripts. The provision of comments to authors should therefore be optional, particularly where reviewers have flagged integrity concerns (Table 1). Confidential comments to the editor allow reviewers to communicate directly with editors, without these comments being returned to authors (Dine et al. 2015; O'Brien et al. 2021). Limited research has been conducted to describe how reviewers use confidential comments, but this option seems to be rarely used to flag ethical concerns (O'Brien et al. 2021). Journals could, therefore, offer better guidance around the option of providing confidential comments, to explain that these comments can include descriptions of integrity concerns. Where authors elect to return no comments to authors, submission of confidential comments to the editor could become a requirement (Table 1). Many revised manuscripts undergo further peer review, particularly if many revisions are requested (Sever 2023). Editorial and peer review of revised manuscripts therefore provide another opportunity to detect and flag integrity concerns that may have been missed earlier (Figure 1). For example, manuscript revision provides an opportunity for editors to request supporting raw data that can sometimes reveal new integrity concerns (Christopher 2021). Journals frequently ask whether reviewers are willing to review revised manuscripts, as re-engaging the same reviewers saves time and allows revisions to be considered by the reviewers who requested them (McKeever 2022). While engaging new peer reviewers may not be welcomed by journals, new reviewers can potentially detect integrity issues that might have been missed earlier (Figure 1). Responses to reviewers and revised manuscripts can also include new indicators of problematic submissions, such as (i) implausibly rapid turn-around of revisions, particularly where revisions require the collection and analysis of new data that authors might not reasonably have been expected to have at hand; and/or author responses that (ii) are poorly worded; (iii) do not address editorial and/or reviewer comments and/or (iv) provide irrelevant new data that were not requested. As revised manuscripts can include new indicators of problematic integrity, the same opportunities to flag integrity concerns should be offered to peer reviewers of revised manuscripts (Table 1). Editor and peer reviewer education should also describe possible signs of paper mill support in revised manuscripts and in author responses to editorial/reviewer comments. We recognise that taking a more adversarial approach to peer review could have unintended consequences. A proportion of integrity concerns could be unfounded; and so desk rejecting manuscripts based on integrity concerns could disadvantage some genuine research and scholarship. This is an important consideration, particularly given the higher stakes that peer review can represent for junior scholars (Meibauer et al. 2025). High rates of desk rejections could also impose additional stress on editors that could adversely impact decision making (Bazerman and Sezer 2016; Wykes and Parkinson 2023). High desk rejection rates could be particularly challenging for smaller or new journals, where editors may be encouraged to send more submissions for peer review. Rapid desk rejections could also allow quick resubmissions of paper mill manuscripts to other journals. These factors highlight the importance of considered desk rejections, where the timeliness of editorial decisions may be less important (Wykes and Parkinson 2023). Encouraging confidential comments to editors could also provide opportunities for reviewers to make vexatious claims to disadvantage competitors (Swanson 2023). While this represents a possibility, it is important to recognise that rival reviewers have other opportunities to disadvantage competitors through their comments to authors. Some journals allow authors to exclude reviewers from peer review to reduce the possibility of vexatious claims or delays. From our experience as both editors and peer reviewers, single reviewer descriptions of integrity concerns seem unlikely to determine editorial decisions. However, peer review processes that allow manuscripts to be (i) declined for peer review due to possible integrity concerns and (ii) receive peer review comments on similar issues could be less susceptible to vexatious claims. Many journal editors have described rising numbers of problematic submissions that are increasingly overwhelming peer review resources and leading to rising numbers of low-value publications. The Swiss Cheese Model allows peer review to be reconsidered from an error detection and accident prevention perspective, where each peer review stage can be considered a new opportunity to detect problematic submissions. The changes that we have suggested could allow journal editors and peer reviewers to more effectively flag problematic submissions, producing a more resilient peer review system and contributing towards a more evidence-based understanding of peer review. More widespread use of best practices and a willingness to constantly update peer review processes to emerging threats (Abalkina et al. 2025; Netzer 2024) could allow better use of valuable peer review resources and reduce unethical publications from paper mills. Jennifer A. Byrne: conceptualization, writing – original draft, writing – review and editing. Anna Abalkina: writing – review and editing, writing – original draft. Jana Christopher: writing – original draft, writing – review and editing. Marie F. Soulière: writing – original draft, writing – review and editing. The authors gratefully acknowledge support from United2Act, a project jointly funded by COPE and STM, and members of the United2Act Research Working Group and Steering Committee for discussions. J.A.B. gratefully acknowledges funding from NHMRC Ideas grant APP2029249 to study publications from paper mills. No large language model was used in any aspect of the preparation or writing of this manuscript. All opinions expressed in this commentary represent the views of the authors and do not represent the views of any listed employer or institution. M.F.S. is employed by Frontiers Media SA. All opinions expressed in this commentary represent the views of the authors and do not represent the views of any listed employer or institution. The other authors declare no conflicts of interest. Data sharing not applicable to this article as no datasets were generated or analysed during the current study.