Discipline-specific open access publishing practices and barriers to change: an evidence-based review

Definition of open access and open access routes

Fifteen years of research into the prevalence of OA have produced a number of different concepts of OA and its sub-types¹. One influential definition of OA is that offered by the 2002 Budapest Open Access Initiative, which understands scholarly outputs as OA if they are both free to read and free to reuse, without any financial, legal, or technical barriers other than gaining access to the internet^11,12. However, a number of bibliometric studies have adopted a more lax definition of OA. Some require only that OA contents are freely available to read online, while disregarding reuse rights^13–16. Others apply the minimum requirement that scholarly articles should be freely available to read online, and assess factors that determine their openness, for example what rights are provided by different types of licences or how articles are stored^11,17,18. Following the latter studies, this study understands OA as scholarly outputs that are free to read online, either on a journal website or through an open repository, and that might or might not be free to reuse. This definition assumes that OA is a spectrum that encompasses a range of components, which determine the degree of openness of a certain publication outlet¹⁹. Different sub-types, so-called "routes" of OA, can be identified, depending on when and where scholarly articles are made available, who makes them available and what rights are provided by different types of licences¹⁷. The following routes are included in this study’s definition of OA: Gold OA, Green OA, Hybrid OA, Delayed OA and Bronze OA. These routes differ in their openness and sustainability across fundamental aspects of OA – reader rights, reuse rights, copyrights, author posting rights and machine readability¹⁹. Some of these routes enjoy general support as sub-types of OA while others remain controversial²⁰. Their definitions are given in Table 1. These routes are understood as exclusive categories and publisher-hosted content trumps self-archived content¹¹. This study does not include "Black OA", which refers to articles shared on illegal pirate sites, for example Sci-Hub, and "Academic Social Networks" (ASNs) or "Free availability" (FA), which describes authors sharing their papers on commercial online social networks like ResearchGate or other websites^{2 11}. Where bibliometric studies differ from our definition of OA, this will be highlighted.

Prevalence and patterns of open access publishing practices: Meta-synthesis of bibliometric studies

The objective of our review is to identify and to synthesize bibliometric studies on the prevalence and patterns of OA publishing across academic disciplines. Such studies explore OA availability "bottom-up" through webbased queries of bibliometric databases such as Web of Science (WoS), Google Scholar (GS) or Scopus, and give uptake metrics for various OA routes. Because significant methodological differences can be identified within this approach, we conducted a meta-synthesis. The aim of a meta-synthesis is to integrate qualitatively, to compare, and to analyse methodologically heterogeneous studies, thereby allowing the emergence of interpretive themes²³. Here, we synthesised the results from bibliometric studies to identify patterns of OA publishing practices. The search was pre-planned and comprehensive, as it aimed to seek all available studies. No date limits were employed. The searches were conducted in August to October 2018 in a systematic way (Figure 1). This involved, first, the querying of the online data bases ScienceOpen, Scopus, WoS and GS. The search was conducted using the following search string: “Discipline” AND “Publish*” AND “Open access” OR “OA”. The selection of the search terms was based on the topic literature. Second, reference lists and bibliographies of all included studies were evaluated for additional publications. Having identified key experts, their GS profiles were also searched for material. In an initial screening stage, two independent reviewers screened titles and abstracts of studies and decided on whether to include respective studies. Studies were excluded that did not meet our selection criteria (Table 2). In a second screening stage, we assessed the full texts and extracted data on reported proportions of publications that were OA from the "Results" sections of included studies.

Figure 1. Search strategy.

Mechanisms and factors shaping open access publishing practices: Narrative review of sociotechnological forces

Our goal in this section is to explain the patterns of OA publishing practices that we observed in the previous section. To do this, we performed a narrative review of the mechanisms and factors that shape OA publishing practices. We recruited an interdisciplinary team of researchers covering the natural and technical sciences, medicine, social sciences, law and the humanities. We did not perform a systematic review of the literature, but developed an analytical framework of socio-cultural and technical factors that shape publishing practices. Each co-author used this framework as a tool for identifying the socio-technical mechanisms and factors that shape OA publishing practices within their own discipline. The evidence included in this review was identified and selected through queries of online databases, including ScienceOpen, Scopus, WoS and GS. Reference lists and bibliographies of relevant studies were evaluated manually for additional evidence.

Prevalence and patterns of open access publishing practices

The characteristics of the studies included in our review are presented in Table 3. In general, studies were concerned with the questions of (1) how much literature is OA across all disciplines and for individual disciplines, and (2) how much literature is published via different OA routes across all disciplines and for individual disciplines. Making use of automated web search strategies, studies assessed whether openly accessible versions of scholarly publications could be found on the web. Within this broad approach, important methodological differences can be identified. This relates to, first, definitions of OA and different OA routes. Some studies only estimated overall OA prevalence levels, but did not assess the relative uptake of different OA routes^{13–15,24,25}. Others did assess the relative importance of Gold and Green OA, but not the uptake levels of other OA sub-types^1,9,17. One study assessed relative uptake levels for Gold, Green, Hybrid and Bronze OA, but excluded Delayed OA from its analyses¹¹. Two further studies estimated uptake levels for Delayed OA, but only as part of "Other OA", together with Hybrid OA, ASNs and other websites¹⁰. A small number of studies included ASNs and FA in their definitions of OA, either as a part of Green OA together with other websites^16,17, as the sub-type "Other OA" merged with Delayed OA, Hybrid OA and other websites¹⁰, or as the sub-type "FA" together with other websites and harvesters¹⁸. Second, bibliometric studies covered different publication years for which they determined OA prevalence levels, spanning 1992²⁴ to 2017¹³. Third, in determining OA prevalence levels, studies used different databases and search strategies. Some studies examined the WoS database or its predecessor Thomson Reuters ISI Web of Knowledge in full^13,24,25, while others assessed random samples of papers indexed in these databases^9,11, or combined them with Scopus¹⁷ or the Social Sciences Citation Index and Humanities Citation Index¹⁸. Another subset of studies examined Scopus either in full or as random samples of articles indexed therein^1,10,14, and one study used GS¹⁵. In assessing whether openly accessible versions of scholarly publications indexed in these databases can be found, some studies searched for their corresponding freely available full text versions via Unpaywall¹³, in the oaDOI database^11,25 or in the 1science database of OA articles¹⁷. Other studies searched for OA versions in GS^14,15 or via Google, either manually¹ or by means of automated robot crawling^9,24. Table 4 shows the main findings of the studies included in our meta-synthesis.

Overall uptake on OA. The figures for the overall prevalence of OA show that OA levels have increased steadily across all disciplines, from 20.4% of all scholarly outputs reported as OA in 2008 (including ASNs and FA)¹⁶, to 23% in 2010⁹ and more than one third of all scholarly outputs being OA in publication years later than 2010: 46.9% for publication years 2011 until 2013 (including ASNs and FA)¹⁰, 54.6% on average in years 2009 and 2014 (including 20.7% ASNs and FA)¹⁸, 36.1% on average between 2009 and 2015¹¹, 66% for publication years between 2009 and 2017¹³, 54.8% in 2014 (including ASNs and FA)¹⁷ and 29.4% in 2016²⁵. We can distinguish between three phases. Dated between the late 1990s and the mid to late 2000s, the first phase can be characterised as a phase of formation: A few fields related to the natural and technical sciences took on a pioneering role in implementing OA, amongst these particularly mathematics, physics and space-related research fields, for which reported OA levels vary across studies between 23.5% for physics & astronomy (including ASNs and FA) and 42% for mathematics^1,9. An exception to this are the fields engineering and chemistry, which feature consistently lower OA levels. The social sciences were also fast in embracing OA, featuring OA prevalence levels only slightly below those reported for the natural sciences^1,9,24. Medical fields were substantially slower in implementing OA than natural and social sciences^1,9,24. The second phase of OA is dated between the late 2000s and the mid 2010s and can be characterized as a period of transformation. For the early period of this phase, OA levels in the natural and technical sciences remained above those observed in other disciplines with reported OA levels between 27% for mathematics and 50% for computer sciences¹⁵. In medicine, OA uptake soon increased substantially, causing OA levels in these fields to equal or surpass OA prevalence in other fields¹⁴. Particularly biomedical research took on a leading role, featuring reported OA levels of 70.6% (including ASNs and FA)¹⁰. During this period, the gap between the natural and technical sciences and medicine on the one side and the social sciences and humanities on the other side widened. The humanities and arts published research outputs to lesser degrees OA, featuring OA levels that vary across studies between 23.3% for visual and performing arts and 35.9% for general arts, humanities and social sciences (both including ASNs and FA)¹⁰. The third phase of OA can be dated after the early 2010s and is a phase of stabilisation, in which differences in the OA publishing patterns across disciplines have become established. Studies consistently show that medical and health-related research fields are taking the leading roles in embracing OA, featuring reported OA uptake levels between 47.8% for clinical medicine and 85% for biomedical research^{11,13,17,18,25}. This is closely followed by physics, mathematics and earth and space sciences^{11,13,17,18,25}. OA uptake in the social sciences is close behind the natural sciences, followed by law, arts and humanities with some distance^{11,13,17,18,25}. Chemistry and engineering feature the lowest OA uptake levels, varying across studies between 15.5% and 35% for chemistry and between 17.4% and 29% for engineering^11,13.

Relative uptake of open access routes. Most OA is published via the Green route, featuring reported uptake levels that vary across studies between 5.9% (publication years 2011–2013), 21% (publication years 2005–2010) and 31% (publication year 2014, including ASN and FA)^10,17,17. Gold OA journals are also of importance for scholarly publishing, even though the relative uptake on Gold OA remains below Green OA for most publication years, with reported prevalence levels between 2% (publication years 2005–2010) and 12.1% (publication years 2011–2013)^{1,10,11,14,18}. Studies that also assessed the relative uptake on Bronze, Hybrid and Delayed OA have revealed that the importance of Bronze OA is comparable to that of Gold OA and that Hybrid and Delayed OA generally are of little importance for scholarly publishing, with less than 5% of all scholarly outputs being published Hybrid or Delayed OA^11,18. ASNs and FA appear to play a highly relevant role for making research outputs openly accessible, featuring levels of 20.7% in 2009 and 2014¹⁸.

Looking at the relative importance of the different OA routes for each discipline, we observe that, for the medical sciences, publication in Gold and Bronze OA journals plays the most important role for making research findings OA, followed by Green OA and, with some distance, Hybrid and Delayed OA. For the natural and technical sciences, we see that there are substantial differences in the OA publishing patterns between different fields: scholars in physics, mathematics, astronomy and biology make large shares of their research outputs openly accessible through the Green route of OA, followed by Bronze OA, Gold OA, and, with some distance, Delayed and Hybrid OA. For scholars in chemistry and biology, Gold OA journals are of greater importance than any other OA route, followed by Green, Bronze and Hybrid OA. For scholars in the social sciences, Green OA is of greater importance for OA publishing than Gold OA, Bronze OA and Hybrid OA. In the humanities and law, scholars make research outputs openly accessible predominantly through publication of articles in Hybrid OA journals, followed by Green OA, Bronze OA and Gold OA^{1,10,11,14,17,18}.

Analytical framework: Social shaping of technology

Previous studies have analysed discipline-specific publishing practices from a range of perspectives. In general, these perspectives originate from science and technology studies (STS), which look at how society, politics and culture shape research and technological innovation, and vice versa. Depending on their understanding of the direction of this relationship, these perspectives can be located on a scale that ranges from technological determinism at the one extreme to social constructionism of technology (SCOT) at the other extreme²⁶. Both positions have been shown to suffer from limitations in explaining scholarly publishing practices⁶. The so-called “social shaping of technology” (SST) perspective that takes an intermediate standing between these extremes proves to be more useful for analysing publishing practices. SST is a theoretical stance that conceives the relationship between technology and society as one of mutual shaping²⁷. Technology is believed to be a social product patterned by the conditions of its creation and use²⁸. Central to technical change are choices made by social actors during the generation and implementation of new technologies²⁹. Which options social actors select is affected by both technical considerations and a range of social and cultural aspects. Thus, social choices influence the contents of technologies. At the same time, technologies have social implications as they shape human action and behaviour²⁷. Following this, scholarly publishing practices can be understood as socio-technical ensembles: the ways in which scholarly outputs are published is affected by the operational choices made by scholars during the implementation and use of communication technologies. These choices are influenced by both technical considerations and socio-cultural aspects. As communication technologies are implemented and used, they in turn affect the ways in which scholars communicate and disseminate their research findings. In order to explain discipline-specific OA publishing practices, it is necessary to examine the socio-cultural and technical factors that affect publishing choices. Based on these assumptions, we have developed an analytical framework that places focus upon technical factors and socio-cultural factors alike when analysing patterns of OA publishing practices (Table 5).

Open access in the medical sciences

Initially, medicine and health-related disciplines were reluctant to adopt OA publishing. From the mid-2000s onwards, the uptake on OA increased substantially and particularly biomedicine took on a leading role in embracing OA. Research outputs are predominantly made OA by publication in Gold OA journals. Hybrid OA, Bronze OA and Green OA are of less importance.

A) Author behaviour and attitudes – Several surveys and interview studies have shown that a large majority of authors support OA publishing, but the reputation of journals, impact factors, and quality and speed of peer review are more important factors determining the choice of publication outlets^30–33. Surveys among academics from lower income countries indicate that the funding of APCs is an important concern, which might explain why authors from resource-limited settings are over-represented among publications in fraudulent journals that charge small fees but do not provide proper editorial and peer review services^34–36.

B) Publisher behaviour and policies – As the OA model is unlikely to generate the same level of income and profit that can be achieved with the subscription model, commercial medical publishers have been reluctant to convert their subscription journals to OA^3,37. The same applies to academic and professional societies³⁸. Some journals have now moved to allowing the self-archiving of submitted manuscripts without embargo periods, while for others self-archiving of accepted versions remains subject to embargo periods of 12 months. Pioneers among OA medical journals include the Journal of Clinical Investigation, which in 1996 became the first major journal to be freely available. Publication in the journal was free initially, but APCs were introduced after the journal lost 40% of its institutional subscribers³⁹. The BMJ followed in 1998, but moved some contents behind a paywall in 2005⁴⁰. The number of OA journals increased considerably from 2000 onwards, with the rapid growth of OA publishers such as the not-for-profit publisher Public Library of Science (PLOS) or the commercial publisher BioMedCentral (BMC). The launch of OA journals by major biomedical research funders^41–43 and the emergence of mega-journals are other factors that facilitate OA⁴⁴.

C) Infrastructure of scholarly communication – OA publishing focuses on Gold OA journals and only a small number of OA institutional and subject repositories has emerged. This is because, first, sufficient funding is available for publication in Gold OA journals. Second, journal publications are of central importance in academic hiring and promotion decisions. Third, there is a large number of high-quality Gold OA journals for authors to publish their research in. An exception to this is the PubMed Central (PMC), which archives full-text scholarly articles and has experienced rapid growth in the late 2000s to early 2010s as the National Institutes of Health (NIH) introduced an OA policy in 2008 that mandates its grantees to deposit the final peer-reviewed version of an article based on NIH-funded research in PMC. The embargo was initially 12 months after publication, but was later shortened to 6 months. Journals have since moved to be compliant with this Green OA mandate⁴⁵.

D) Structural and institutional factors – The main type of work products are journal articles. As research in the medical sciences and related fields mostly is funded by project-specific grants, it is fairly easy to integrate APCs into existing funding structures.

E) Open access mandates and policies – Evolving national and institutional OA policies and mandates have accelerated OA publishing. A substantial number of national governments have moved to require scholars to make their articles OA if based on publicly-funded research. Scholars can either follow the Gold or the Green route and are granted embargo periods of 6 or 12 months to comply with the latter¹³. Major funders of (bio)medical research also play an active role in promoting OA. Since 2014, journal articles and book chapters based on research funded by the World Health Organization (WHO) have to be published in either an Gold or Hybrid OA journal or in a subscription journal that allows the depositing of accepted versions in PMC no later than 12 months after publication⁴⁶. The Wellcome Trust requires articles to be published in OA journals where a journal makes this option available and to be deposited as the accepted version in an open repositories no later than 6 months. Both funders provide repository infrastructures (PMC for NIH and PMC or PMC Europe for Wellcome Trust) and APC funds⁴⁷. The Wellcome Trust has launched its own OA journal, Wellcome Open Research, enabling its grant recipients to publish OA for free⁴¹. In contrast to the USA, the policy environment in the UK favoured Gold and Hybrid OA, with particularly high uptake in the life sciences and increasing costs⁴⁸.

Open access in the natural and technical sciences

For most publication years, the natural and technical sciences show the highest OA prevalence rates amongst all disciplines. There are differences in the publishing patterns between the sub-disciplines. Scholars in physics, mathematics, astronomy and information technology were early pioneers of OA. In biology, OA uptake increased in the early 2000s. Engineering and chemistry feature OA prevalence rates that are consistently lower.

A) Author behaviour and attitudes – The distribution of preprints has a long tradition in physics, mathematics, astronomy, and information technology. In biology, scholars initially were slower in embracing the idea of sharing preprints, but with the launch of platforms like PeerJ Preprints and bioRxiv in 2013, preprints took off⁴⁹. Surveys have revealed that, to scholars within these fields, rapid publication, high visibility and large readership appear to be the most important factors for choosing a publication outlet, and that scholars associate these features with repositories^50,51. Adding to this, scholars generally show high levels of familiarity with OA^16,52. In contrast, scholars in chemistry and engineering value publication in journals over self-archiving, causing Gold OA to play a bigger role than Green OA⁵¹. Chemistry and engineering further show a particularly low uptake on OA. This might be because scholars have doubts about the quality of peer review in OA journals and are concerned that this might translate into low-quality publications^53,54.

B) Publisher behaviour and policies – Commercial publishers and learned societies have been slow in embracing the idea of OA. This is because they face a potential loss of revenues in switching from a subscription model to an APC model^55,56. Also, general concerns about the quality of OA journals are not only shared by scholars but also by publishers⁵³. As a result, most of the major commercial publishers as well as learned societies have been reluctant to convert their existing journals to OA or to set up new OA journals. An exception to this are few large publishing houses that set up new OA journals in disciplines that do not have a culture of preprint distribution, such as chemistry. In disciplines where there is a preprint culture, publishers are relaxing policies on prior publication and enable manuscripts deposited in repositories to be directly submitted to their journals⁵³.

C) Infrastructure of scholarly communication – In physics, mathematics, astronomy, information technology and, with some delay, in biology, scholars became used to sharing their research outputs openly making use of open repositories⁴. Originally established within high energy physics, arXiv is the most popular repository and is now used by scholars in most fields of the natural sciences. Its concept has resulted in a number of discipline-specific repositories in other sub-fields, for example bioRXiv for biology⁴⁹. In the light of this publication culture, relatively few OA journals have emerged within these fields. In fields where there is a smaller culture of self-archiving in repositories, most particularly in chemistry and engineering, and initially in biology, the number of OA journals has grown slowly but steadily. These journals cover a variety of specific subject areas, are peer-reviewed, and, for the most part, published in English^53,57. In biology, preprints finally took off after 2013 with the launch of platforms such as launch of PeerJ Preprints and bioRxiv⁴⁹.

D) Structural and institutional factors – The main types of work products are journal articles, preprints and conference proceedings. Researchers have reported that the process of self-archiving in repositories is easy and little time-consuming⁵¹. Research is in large parts funded by project-specific grants, which would make it fairly easy for scholars to integrate APCs for Gold or Hybrid OA journals into existing funding structures. A structural factor that limits OA uptake particularly in chemistry and engineering, is that these fields are industry-oriented, which is incompatible with wide and open knowledge dissemination⁵⁸. This adds to the fact that, particularly within engineering, the focus is rather national than international as products are mostly produced for domestic markets^58,59. Consequently, large numbers of publications are more practice-oriented and published in closed-access journals that are partly financed by advertising⁵⁷.

E) Open access mandates and policies – There are strong OA mandates, requiring scholars to make their outputs OA if based on publicly-funded research by following either the Gold or the Green OA route. Scholars are granted embargo periods of 6 or 12 months to comply with the latter¹³. Besides public funders, CERN and the Sponsoring Consortium for OA Publishing in Particle Physics (SCOAP) play leading roles in promoting OA. SCOAP is an international partnership that aims to provide funding for the conversion of high-energy physics journals to OA. Within this scheme, libraries and research centers either pay reduced subscription fees for participating journals or stop paying altogether. Saved monies are used to pay publishers up front to publish OA articles⁶⁰. This enables scholars to publish OA without straining own research funds⁶¹. CERN requires its scholars to publish their articles in journals covered by SCOAP. When circumstances require publication in other journals, APCs must be covered by funds from outside the CERN Budget. Where this is not possible, authors may request special permission and funds from CERN⁶².

Open access in the social sciences

The OA uptake in the social sciences is higher than in most disciplines of the humanities, but remains below the medical and natural sciences. For social scientists, open repositories appear to be of central importance for making research outputs OA. Gold OA, Hybrid OA and Bronze OA play a less important role^1,9,11,17,18.

A) Author behaviour and attitudes – Author surveys reveal that the awareness of OA publishing is low, and that OA publication outlets have not yet fully become part of the workflow for social scientists^52,63. The knowledge of OA journals and repositories however appears to grow. Particularly young researchers report high levels of OA engagement⁶³. Most social scientists support the idea of OA in principle, but stringent quality control, improvement of the manuscript before publication and journal prestige appear to outweigh OA as journal selection criteria^64,65. This adds to the fact that scholars and learned societies are concerned about the quality of peer review and editorial services in OA outlets⁶⁶. Of relevance is also that the monograph has a central place in the culture of publishing and is relevant to career advancement^65,67. Monographs are less likely to be published OA because of authors’ concerns over restricted editorial services, difficulties in financing Book Processing Charges (BPCs) and doubts if unestablished OA publishers are able to translate authors’ efforts into reputational gain⁶⁸.

B) Publisher behaviour and policies – Few publishers have converted existing subscription journals to OA or set up new OA journals. Key journals remain closed. Amongst other factors, this relates to publishers fearing that authors will not be able fund APCs or that switching to OA will result in a loss of prestige⁶⁵. One notable exception is SAGE Open in 2011 – the OA mega journal model already popular in the natural and medical sciences⁶⁹. In addition, a few OA journals were launched by academic or professional societies⁵¹. For some journals, such as the Historical Social Research, it has become common practice to make contents automatically OA after two years⁷⁰. In addition, a large variety of new economic models of OA publishing has emerged that offers viable alternatives to author-payment model. To name only two, this includes Knowledge Unlatched (KU) and the Open Library of Humanities (OLH)⁷¹. Another innovative business model of OA publishing that has gained some popularity is the so-called “freemium” model, which makes HTML versions of articles and books openly available, while PDF and ePub formats are accessible only to subscribers^72,73.

C) Infrastructures of scholarly communication – Some attempts have been made to promote repositories. Authors are now able to choose from more than 200 different OA repositories, the most of which are institutional or subject repositories^74,75. Social scientists have however been slow to adopt Green OA, which might be because readers consider the article version of a manuscript as important and are likely to distrust versions of articles held in a repository⁷⁶. Institutional repositories predominantly host faculty working papers, while subject repositories have become part of the workflow for social scientists. Prominent examples are the Social Science Research Network, the Social Science Open Access Repository and the preprint server SocArXiv. Gold OA is also of little importance to social scientists. The few existing OA journals are restricted to highly specified sub-disciplines with limited impact and small readership⁷⁷.

D) Structural and institutional factors – Monographs are one of the main work products in the social sciences and highly relevant for academic career advancement. Besides author concerns over prestige and standards of editorial services of OA monograph publishers, the high costs and procedural complexities associated with producing monographs are important factors restricting the uptake on OA of monographs⁷⁸. In addition to this, social scientists have reported to face significant difficulties in access to grant funding for both APCs and BPCs, as most research in the social sciences is not done by means of project-specific funding³².

E) Open access mandates and policies – Scholars in the social sciences face similar OA requirements as the natural and medical sciences, albeit with some special regulations. Monographs are generally not included in OA mandates. Most public funders only recommend OA for monographs. One of the few exceptions is the Swiss National Science Foundation (SNSF), which demands the OA publication of monographs and provides respective funding for BPCs^68,79. The social sciences commonly also are granted longer embargo periods for archiving articles after publication in a subscription journal. While embargo periods of 6 or 12 months are the default for the natural and medical sciences, social scientists usually are granted 12 or 24 months^13,80.

Open access in the humanities

The OA uptake in the humanities is lower than in most other fields. For scholars, open repositories appear to be of greater importance than Gold OA journals^9–11,17. Not much information is available on the importance of Hybrid and Bronze OA. One recent study has indicated that Hybrid OA is of central importance for the humanities and that Bronze OA plays a similar role as Gold OA¹¹.

A) Author behaviour and attitudes – Authors operate within a symbolic economy of prestige that is usually among the prime motivations in choice of publication venue⁸¹. The relative prestige of publications is determined by a scarcity correlation with a shortage of labour on hiring, tenure, and grant panels, although most humanities fields use an informal hierarchy of publications rather than quantitative measures such as the Impact Factor⁸². Further, academics and learned societies have often been opposed to OA, for a variety of reasons that range from concerns to misunderstandings, worries about licensing and plagiarism, or fears for the standing of their members^54,83. In addition to this, humanities scholars show fairly low levels of awareness of OA and OA publication outlets in their fields⁸⁴. That said, there are signs of a cultural shift with new economic models that do not rely on author payments, such as KU, OLH, Open Humanities Press, Open Book Publishers, Punctum Books, which appear to have some traction with some humanities scholars. It is tempting to posit that humanities scholars are less driven by technological change than counterparts in science disciplines, and thereby less inclined towards digital and open publishing solutions. A recent report however demonstrates that research and communication in the humanities are largely taking place in an electronic environment, which includes blogs or wikis, and that the distribution of scientific information occurs simultaneously through print and digital media, with the latter gaining importance⁸⁵.

B) Publisher behaviour and policies – The main concern driving humanities publishers is ongoing sustainability of their operations. In switching to an APC or BPC model, publishers fear that their academic authors will not be able to pay. It is also clear that highly selective publication models, which are common in the humanities, are more difficult to run, economically, on an OA basis. Hence there is little movement towards a fully Gold OA ecosystem, although it is unclear what impact the recently announced pan-European initiative, Plan S, may have upon this. That said, most humanities publishers are compliant with green OA mandates⁸⁶. On the other hand, some humanities scholars have argued that a longer citation half-life (particularly for monographs) should translate to longer embargo periods, although this does not necessarily match up to sales half-lives⁸⁷. Some publishers now offer Hybrid OA for their existing subscription journals⁸¹. This allows authors to conform with most OA mandates while publishing their work in familiar journals by traditional publishers. This might explain why Hybrid OA is popular in these disciplines. Despite some disciplines having healthy cultures of offline working paper circulation (philosophy, for instance), preprints have not taken off. Policies on prior publication remain tight, especially in prestigious venues.

C) Infrastructure of scholarly communication – In addition to institutional repositories, there has been a growth of subject repositories, such as CORE, the Open Access Repository for the Humanities, which is operated by Modern Language Association of America. There has also been a prominent culture, for many years, of scholarled OA journal and book publications⁸¹. There is no preprint infrastructure at a comparative scale to arXiv. Further, for long-form reading, print remains a crucial resource and scholars often report that they do not wish to read such works in a digital format.

D) Structural and institutional factors – The high costs of producing monographs are a key structural factor that limits OA^67,78. Further, most research work in the humanities does not receive project-specific funding, making it difficult to integrate APCs into grants. That the humanities are often of lesser importance in institutional hierarchies also means that it can be difficult to secure funding. The slow cycle of producing long-form outputs is also problematic for OA, as the time investment (and hoped-for credit) is greater than those of a journal article, leading scholars into conservative behaviours. There are also substantial challenges around third-party rights and reuse of images, particularly within disciplines such as Art History, where it can be difficult to negotiate re-use rights for dissemination. Some disciplines, such as creative writing, have outward facing cultures that rely on sales, which works poorly under OA. The production of such outputs may have a research process behind them and various institutional policies will regard those as scholarly undertakings. The extent to which such work should be exempted from OA mandates remains an ongoing debate.

E) Open access mandates and policies – In national cultures, such as in the UK, the humanities face similar OA requirements as the social sciences, involving monographs being excluded from OA mandates and embargo periods of 12 or 24 months for the archiving of journal articles after publication in a subscription-journal. A few research foundations, such as the Wellcome Trust, will pay for Gold OA to monographs in the medical humanities. It appears likely, given recent moves among European funders, that policies around lengthened embargo periods for the humanities will be harmonized with other disciplines, e.g. Plan S, which does not allow any embargoes⁸⁸.

Open access in law

The transition to OA of legal literature is in its infancy. Legal studies feature some of the lowest OA rates²⁴.

A) Author behaviour and attitudes – Scholars have been reluctant to adopt OA despite agreeing that the field would benefit from journals that publish OA^89–91. Many authors either are not aware of OA or have little incentive to publish OA⁹², but the field is slowly moving with networks for OA being established, such as the German-speaking network jurOA (established in 2018). It is common practice that academics and practicing lawyers publish in the same legal journals or commentaries. Some practicing lawyers might even prefer to publish in law journals behind paywalls, thereby guaranteeing exclusive access to their knowledge⁹³. Because of the high relevance of national legal systems, large parts of the literature are written in the languages of these countries and published in journals or books operated in the same countries. The argument that OA enables worldwide readership is of limited relevance. On the other hand, many legal issues are of interest not only to legal scholars but also to the media and politics⁹⁴. The role of electronic media in supporting scholarly communication and dissemination of research findings is growing but important databases (e.g. HeinOnline in the United States or BeckOnline in Germany) are paywalled⁹⁵.

B) Publisher behaviour and policies – In the U.S., many law reviews are published by law schools, not by for-profit publishers^95–97. In contrast to commercial publishers, law schools do not have the usual incentives to oppose OA and a growing number of their journals are converted to OA. This is different in jurisdictions outside the US where legal scholarship is generally published by commercial publishers^89,97. Due to the small demand for OA by legal scholars, there are little to no incentives for for-profit publishers to set up new OA journals or book series or to convert existing subscription journals to OA. There are some notable exceptions. In recent years, some OA law journals have been set up that are predominantly community-driven (e.g. Journal of Intellectual Property, Information Technology and Electronic Commerce Law and Forum Historiae Iuris in Germany or sui generis in Switzerland). According to the DOAJ, there are about 260 OA law journals. OA law journals from the US are in large part not listed, although it is not clear why this is the case. The Creative Commons List of OA Law Adopting Journals lists 37 OA law journals but most of the 17 Harvard Law School OA journals are missing^98,99.

C) Infrastructure of scholarly communication – Most OA journals and open repositories are operated by universities and their law departments. Most universities in the U.S. have their own repositories and also publish their own legal OA working paper series. This idea gains some traction in other countries, for example in Germany, the Netherlands or Italy. Prominent examples of university-led OA journals involve Stanford Technology Law Review, Harvard Human Rights Journal, Bucerius Law Journal or the International Journal of Communications Law & Policy. There is only a limited number of disciplinary repositories and the uptake is slow. In the U.S. and in international law, the most popular disciplinary repository is SSRN, which is now owned by Elsevier. In English-speaking legal scholarship, scholars find it difficult to build reputation without being represented in SSRN¹⁰⁰. A growing number of universities is further providing support for setting up OA journals or transforming closed to OA journals (for example, by providing an Open Journal Systems infrastructure). Since practicing lawyers and scholars work almost exclusively with texts, OA infrastructures do not have to meet demanding technical requirements.

D) Structural and institutional factors – There are three types of work products: monographs, journal articles and commentaries covering a specific law. PhD theses are predominantly published as monographs and many universities routinely make PhD theses OA. While the authors of legal books are mostly academics, this is different for journal articles and legal commentaries where both academics and practitioners contribute. As a result, not only scholars and universities, but also practicing lawyers need to be convinced to move to OA. One possible way to foster OA might be to encourage academics and practitioners to publish in different journals and commentaries. Here, academics could publish in scientific OA journals and practitioners could keep using closed access journals and commentaries, which would be more practice-oriented.

E) Open access mandates and policies – OA mandates by public funding agencies and research foundations only have limited impact since legal research is relatively inexpensive and does not depend on third party funding in large parts⁹⁶. As law is often considered as a discipline related to the humanities, scholars in this field face the same OA requirements as the social sciences and humanities, including relatively long embargo periods for Green OA and monographs that are excluded from OA requirements. It can be assumed that OA mandates by universities will have a greater potential to foster change⁷ An important alternative to top-down OA mandates are OA policies from law schools and non-binding statements promoting OA. In 2009, the directors of the law libraries of 12 US Universities signed the Durham Statement on OA to Legal Scholarship, which urges law schools to make their scholarship immediately available upon publication in stable, open and digital formats¹⁰².