The Comparative Sociology of Legal Doctrine: Thoughts on a Research Program

Abstract In the context of the encounter of UK and German socio-legal studies in this issue, this Article develops preliminary thoughts on a research agenda for the comparative interdisciplinary empirical study of legal doctrine. Based on a working definition of doctrine as an institutionally legitimized practice of making statements on the law, it presents an overview of sociological and comparative theorizing about doctrine in Germany, and of the data and methods being used to study it, in order to identify similar or diverging trends in the UK and elsewhere. This Article aims to show that legal doctrine, which is often regarded by non-lawyers as arcane and/or tedious, is an interesting and important subject for comparative socio-legal research.

This rift might be the reason that the doctrinal study of law has received surprisingly little attention from socio-legal scholars. 5 Though vivid, the often-used distinction between the "law on the books" and the "law in action" is unhelpful in this respect, as long as it conjures the image of a body of text on paper-"black-letter law"-which is largely irrelevant for the "real" law out there in society. This Article argues that it is precisely the connection between law on the books and the law in action that makes studying legal doctrine, from a sociological and comparative perspective, in its various forms worthwhile. Instead of looking at doctrine as the antithesis of their work, socio-legal scholars might gain insight about the social mechanisms of legal knowledge production. As a side effect, this research focus might help enhance collaboration between doctrinal and non-doctrinal scholars because both sides are necessary for this endeavor to be successful.
When I speak of "doctrine," I use this term as "legal dogmatics," which would be etymologically closer to the German Rechtsdogmatik although it is much less commonly used. 6 Both "doctrine" (from Latin doctrina) and its continental sibling concepts that are derived from the Greek dogma have a double etymology that provide notions of both craftsmanship and religious orthodoxy. 7 The traditional German understanding of statute-based Rechtsdogmatik has been defined as the "academic study of the law," 8 which expresses the close connection of German doctrine to legal scholarship. In the UK, doctrine has been defined to express "authoritative juridical ideas that may direct the course of legal decisions," 9 which hints at the high influence of courts in the development of doctrinal statements. It is clear that "doctrine" is what lawyers deal with and that it goes beyond positive law. As I will argue in Section D, a socio-legal analysis of doctrine will look beyond ideas and texts and look at social practices of making statements about what the law is-within the institutions-giving these statements authority and legitimacy.
The following sections present some preliminary thoughts on one of many possible research agendas for the comparative empirical study of legal doctrine. After a short survey on the state of the art, I will justify why it is important to look more closely at legal doctrine, provide a working definition of doctrine as an institutionally legitimized practice of making statements on the law, and give an overview about empirical theorizing about doctrine and about data and methods that are being used to study doctrine in Germany. In line with the exploratory character of the workshop that gave rise to this Special Issue and the early stage of my project, 10 this Article does not attempt to give a comprehensive picture of existing research. Instead, I will be focusing on a few exemplary lines of research in Germany to show that there is a lot to be learned by looking at doctrine from a sociological perspective. My hope is to contribute conceptually to a future Sociology of doctrine which is done comparatively-with attention to the social, political, and historical context-while using international and interdisciplinary collaboration. 5 See Section B, below. 6 The Google Books Ngram Viewer shows almost no occurrences of "legal dogmatics" until the mid-1970s, with a peak in the mid-1980s, but even then "legal doctrine" occurs five times more frequently. See GOOGLE, Google Books Ngram Viewer, https://tinyurl.com/y7j9erjy (last visited May 23, 2020). 7 The meaning of the original Latin and Greek terms refer to teachings or to established rules of a craft, for example, in medicine. In early Christian Theology, doctrina and dogma continued to be understood as teachings or decisions-based on the exegesis of biblical texts-that answered a specific question. The modern connotation of officially ordained truths that are not to be questioned-expressed, for example, in the term "dogmatism"-was only a later development. Getzler, supra note 7, at 2. 10 This Article was motivated by the workshop and written afterwards, which did not leave enough time to integrate a survey of the UK research landscape.

B. An Emerging Research Program on Empirical and Comparative Study of Doctrine
In a 2004 article, Ingo Schulz-Schaeffer remarks that Sociology of law has, "from the beginning up to today, shown very little interest for the doctrinal study of law, i.e. the practice of interpretation of the codified positive law in jurisprudence (Jurisprudenz)." 11 He cites a similar diagnosis to that of Niklas Luhmann in 1986, where he finds Luhmann's statement that "there is no adequate Sociology of legal doctrine" 12 still holds. Schulz-Schaeffer found it bewildering that the empirical study of a social field such as law would almost completely disregard what most legal scholars, and certainly those in Germany, consider the "core" of their enterprise. 13 Another sixteen years later, have things changed? There is little evidence that it has, at least in a systematic way. No German textbook on the Sociology of law treats Rechtsdogmatik in depth-mostly, it serves as a reference point for what the Sociology of law is not. 14 In the UK, the situation seems not much different. The debates which have been held in the last few decades on the question as to whether "doctrinal legal studies" have academic credentials at all, 15 have produced a number of important studies that reflect on the social practice of the production of legal doctrine. 16 However, there seems to be no systematic empirical research on legal doctrine itself. 17 Therefore, it is not surprising that, given this gap in research at the national level, systematic comparative empirical research on the subject is hard to come by. 18 A major challenge for this research is that it is quite unclear what terms like Rechtsdogmatik, 19 la doctrine, 20 or legal doctrine/dogmatics/jurisprudence actually refer to when seen from a comparative perspective. One indication of this is the quote by Schulz-Schaeffer above, whose definition of the doctrinal study of law as "the practice of interpretation of the codified positive law in jurisprudence" does not work very well in common law jurisdictions such as England, Wales, or the U.S. 21 There, "doctrine" is mainly equated with judicial lawmaking, 22 while "doctrinal analysis" means, in the majority of cases, the examination of "the content of a legal opinion to evaluate whether it was effectively reasoned or to explore its implications for future cases." 23 Even if the importance of statutory law has been steadily increasing, the main debate seems to center on 11 Ingo Schulz-Schaeffer, Rechtsdogmatik als Gegenstand der Rechtssoziologie: für eine Rechtssoziologie "mit noch mehr Recht," 25 ZEITSCHRIFT FÜR RECHTSSOZIOLOGIE 141, 141 (2004) (author translation). 12 Admittedly, Luhmann would not consider any sociological theory on the subject to be theoretically "adequate" unless it were derived from System Theory. 13 See the role of judicial precedent in determining the law of the land. 24 It is clear that doctrine is about making authoritative statements about the law, but it is less clear what this entails in practice, and what the role of courts, legal scholarship, and lawyers in general is within this practice. The ambiguity of the term "doctrine" is not due to "the lack of a supra-jurisdictional lingua franca." 25 The problem is more fundamental. As I will argue, national forms of "doctrine" are not primarily systems of thought, but institutionally framed social practices inseparably connected with temporal-spatial social context of the individual nations.
The challenge of undertaking comparative empirical research on doctrine is thus threefold. First, given the multiplicity of concepts, we need to find a suitable "sociological concept" of "doctrine," which will work across legal cultures and histories and which can be operationalized in very different contexts. If such a concept can be found, the second challenge is to define the comparative "research questions." It is to be expected that the questions researchers are interested in will differ substantively in terms of their legal and academic context, because both the normative and empirical studies of law have very different trajectories in different countries. 26 Third, given the vast array of theoretical approaches and empirical methods available to social scientists, such a research program will have to decide on the right mix of these "theories and methods"-determining which will best serve to answer the research questions. It seems plausible to assume that no single theory or method will be sufficient.
These challenges are further complicated by the fact that such a research program is by definition an interdisciplinary enterprise that involves social scientists as well as lawyers. 27 Fortunately, it seems that today, the unproductive antagonisms of the past are slowly being overcome. 28 Legal and socio-legal researchers-at least in both disciplines' cutting edge research-are taking each other seriously and are working together to better understand "the force of law." 29 Despite this, significant differences remain in the kind of questions legal and socio-legal scholars are interested in, how they define problems and concepts, and what kind of methods they are trained in and which they find relevant to their research questions. 30 Such a project, I argue, needs input from many disciplines. First, it should entail a strong historical component. The great variety of legal systems and cultures makes it obvious that law is a historically contingent, path-dependent phenomenon. 31 The specific form in which a practice of legal doctrine can be observed in a particular legal system and geographic area is thus a consequence of lengthy historical developments that shape discourses and thought patterns. The social practice of legal doctrine is subject to constant change, whereby the interesting question  concerns which elements remain constant over a long period of time and which elements must be adapted to social developments. Thus, any research on these differences must include insights from legal history, in particular the socio-historical study of the legal method. Luckily, we can build on a large body of historical-comparative work on the development of doctrinal practices. 32 We also need to involve and integrate the knowledge about legal doctrine that exists in the research field of comparative law. Comparative lawyers know that, without knowledge of contextual factors such as "legal culture, legal argumentation, judicial decision making, styles of legal writing, diverging approaches to legal sources and to statutory interpretation (e.g., the use of travaux préparatoires), the role of legal doctrine, the respective role of the legal professions, the role of form in law in relation to substance," 33 any comparison between laws and legal systems will be deficient. Additionally, there is increasing interest in connecting comparative law with socio-legal theory and methods. 34 However, if the Oxford Handbook of Comparative Law is any indication of the current state of the art, it seems like the phenomenon of doctrine or, in a broader sense, the legal method, is not regarded as a topic that requires a separate chapter. 35

C. Why Comparing Legal Doctrine is Important
Identifying a gap in research says little about its relevance. Why should we study doctrinal practices beyond the fact that it is still possible to say something new? One reason is that from a sociological perspective, legal doctrine is about the power to make decisions. Lawyers and legal scholars use doctrinal arguments in their attempt to influence, inter alia, administrative agencies and the courts, and judges use it to justify their decisions. This has two implications: An analytical one that concerns academic theory development, and a "critical legal studies" one concerning the social and political legitimacy of doctrinal power. "legal" factors is insignificant in explaining the court's rulings, compared to ideological and strategic considerations. 37 No matter how convincing one finds radical or simplified versions of the legal indeterminacy thesis, legal realists' annihilation of law's pretenses to be an objective "science" has, by now, been almost universally accepted, irrespective of the conclusions that one draws from that insight. 38 Many scholars do not believe that doctrine is simply a smokescreen for "something else," at least not in all cases. Instead, their data points them to the assumption that doctrine does actually influence the behavior of judicial or other actors by constraining, or positively influencing, the available outcomes. 39 From a sociological perspective, it is necessary to clarify how the knowledge about "what the law is" is produced, and what social mechanisms are at play when doctrinal practices are involved in the social construction and reproduction of legal knowledge. This goes beyond simply stating causal effects evidenced by statistical correlations in our data, as valuable as such empirical knowledge is. Socio-legal scholars are typically also interested in how those empirical insights fit into existing social-scientific theorizing. In addition, the picture we will get will be very complex, and we can expect each area of law to function very differently-criminal law's doctrinal practices are different from public law's, and, say, family law and commercial law are worlds apart. There will be empirical cases where doctrine truly is nothing but a rationalization of extra-legal motivations; in other cases, we might find that it actually constrains the range of possible legal outcomes.
In contrast, the "critical legal studies" aspect concerns the fact that looking at what lawyers do or say is not just a special application of the Sociology of knowledge or the Sociology of professions. 40 Rather, it leads to the question of how much influence the legal profession has on central political and social decisions, and to what extent this influence can be justified-or instead-in what respects this influence has to be criticized. Thus, the question about how legal knowledge is produced also becomes a problem of democratic theory and the rule of law. 41 It needs to be empirically analyzed, not with the primary aim of "unmasking" and debunking its pretenses, but of making its mechanisms transparent and open for critical discussion. As Dieter Grimm has argued, if a legal norm finds its final form not at the time of its entering into force, but at the time of its application in a specific case, then the rules and metarules of its application are as important as the  38 Duxbury, supra note 3; Brian Z. Tamanaha, Understanding Legal Realism, 87 TEX. L. REV. 731 (2008). The legal realists in the United States were not the first to point this out, but their influence on legal thinking was much stronger than that of their precursors and counterparts in Europe. See also Klaas Hendrik Eller, Comparative Genealogies of "Contract and Society," in this issue. In Germany, the "scientific" basis of "legal science" is still an important topic. See, e.g., HELMUTH SCHULZE-FIELITZ, STAATSRECHTSLEHRE ALS WISSENSCHAFT (2017). norm itself. 42 As the method of interpretation can drastically change the meaning of a legal rule, it is not surprising that, as Grimm points out, most important debates in German jurisprudence have concerned themselves with methods rather than substantive content. 43 The power to interpret legal norms 44 implies the power to choose the rules of interpretation. This power is always shared with the community to which doctrinal texts are addressed, because the approval of this audience is critical to the authority of the interpreter. 45 However, the takeaway is that when we are talking about doctrine, we are always also talking about power issues. This is obvious in high-level cases in apex courts on a national or international level, but equally true for lower-level courts, 46 or questions of legal education 47 or career paths in legal academia. 48

D. Legal Doctrine as Institutionally Legitimated Practice
Before turning to the questions that a comparative inquiry might address, it is necessary to define the concept of doctrine that such an inquiry might be based upon. As comparative lawyers know, the use of one's own vocabulary to describe a different legal system is highly problematic. The same is true for a socio-legal approach. One can introduce a new, alien vocabulary, as System Theory does, to get rid of historical and cultural connotations. 49 Another option is to redefine the existing one-with Max Weber as the obvious example 50 . The advantage with the latter approach is that the resulting analysis is more accessible, in particular when dealing with an interdisciplinary audience, and that approach is chosen for this Article. However, it is important to keep in mind that one has to distinguish between the analytical concept of doctrine as used in this Article to cover doctrinal practices in general, and the term as it is used when describing actual "doctrine" as it is understood in various English-language legal systems.
In contrast to legal philosophy, a sociological perspective will define terms that refer to observable practices that go beyond the systems of thought that are communicated mainly through printed texts. Texts are the outcome of a whole chain of events in which actors do something; ideas are developed and communicated in social contexts which make some ideas easier to express than others. 51 Doctrinal practice usually requires making arguments that are considered to be "legal" by the local epistemic community of lawyers 52 at a particular place and time. In all instances, "the normative content of any doctrine will fall to be determined by the dynamic interpretation of the legal community." 53 This is why I argue that from a sociological perspective, doctrine refers to institutionally legitimized practices of making statements on what the law is. Defining doctrine as "making statements on what the law is" is hardly original and probably not controversial. The stress here is on "institutionally legitimized," because it signals the context-sensitivity of the approach. The form and behavior of legal institutions varies significantly in different locations, as do the ways these institutions confer legitimacy-in its empirical sense-on its members to make authoritative statements. This way of understanding doctrine as a social practice is general enough to cover the very distinct legal cultures in the UK and Germany without claiming to provide a universal definition. 54 Doctrinal practices can be observed in judicial decision-making, in legal advocacy, and in legal scholarship. Each use involves different, but partly overlapping, institutionalized contexts: The judicial system, the market for legal services, and the academy. The first form has been thoroughly studied in the U.S. context, with a focus on higher courts, 55 and with the qualification that the "mainstream" research held for a long time that the actual impact of doctrine on judicial decision making was negligible. Lawyers have been a popular research object. 56 Lawyers use "applied doctrine," ready-made pieces of argumentation that do not have to be consistent as long as they are effective. For them, "legal expertise," which entails much more than strictly legal knowledge, 57 is much more important than the doctrinal quality of their argument. However, recent research on strategic litigation and "cause lawyering" 58 sheds a light on the attempts by lawyer activists to influence doctrine in order to change political or social outcomes.
The third form of doctrine, legal scholarship, is developed mainly, but not exclusively, at universities. For Susan Bartie, in the case of the UK, it is controversial to try and "define a 'standard' form of legal scholarship in circumstances where the concept of law and how it ought to be studied has been in a state of constant flux". 59 Bartie identifies the "core" of doctrinal legal scholarship, or the "concept of 'doctrinalism' or 'black letter law'" in the following way: "[F]ocusing on legal principle (largely that generated by courts but also the legislature); basing argument and prescription on a normative premise which is not unpacked or explained; reacting to events comprising of changes to the law by judges or legislators; and, looking for deficiencies in legal principles, Getzler, supra note 7, at 173. 54 Such an understanding is part of what Robert Merton has called "theories of the medium range," which are "theories that lie between the minor but necessary working hypotheses that evolve in abundance during day-to-day research and the allinclusive systematic efforts to develop a unified theory that will explain all the observed uniformities of social behavior, social organization and social change." ROBERT K. MERTON, SOC. THEORY AND SOCIAL STRUCTURE 39 (1957). On the difference between normative and empirical legitimacy, see Rodney Barker, Legitimacy: The Identity of the Accused, 42 POL. STUD. 101, 101-02 (1994) (providing a succinct summary on the difference). 55 The advanced state of research is evidenced by the existence of specialized handbooks such as the ROUTLEDGE HANDBOOK OF 58 See, e.g., Lisa Hahn, Strategische Prozessführung, in ZEITSCHRIFT FÜR RECHTSSOZIOLOGIE 5-32 (2019). 59 Bartie, supra note 13, at 349. suggesting ways to improve them or clarifying the law so that judges or legislators can better understand their development." For her, the methodology adopted is "likened to that of the courts with the primary focus resting on the internal logic of judgments or statute[s]." 60 Despite the seemingly stronger continuity and stability of the practice of doctrinal analysis in Germany, no consensus exists about what exactly Rechtsdogmatik means. 61 German lawyers, when speaking of it, refer to texts-such as legal decisions, law review articles, commentary literature, or monographs. "Rechtsdogmatik," according to Christian Bumke, "endeavours to sift through and to secure the ideas and insights about the law. To this end, it forms and develops legal concepts or principles and organizes the legal material" 62 for the use in judicial argument and legal education. There is no consensus as to whether positive law is to be considered part of "Rechtsdogmatik." 63 Both descriptions of doctrine hint at the generative, or creative, aspect of doctrinal legal scholarship only in passing. For Bumke, legal dogmatics "forms and develops legal concept or principles" only to the end of systematizing the law that is somehow "out there." Bartie equally portrays doctrinal analysis in the subservient role of a service provider for judges and legislators, which might occasionally make suggestions to improve legal principles. Legal doctrinal scholarship, in its many forms, is not simply reproducing decisions by legislatures and courts, but often "creating" legal principles, interpretative choices, and other normative ideas which are picked up and sanctified as law later on in the courts or in Parliament. As a rule, legal doctrinal texts aim to become part of legal knowledge-meaning they are read and cited by other lawyers. They create new law inasmuch as they do not simply reproduce something given, but make a choice as to what should count as the law. Dogmatic texts contain normative statements that, ultimately, are meant to be used in a judicial decision. In this way, a doctrinal text unfolds social effectiveness in a completely different way than, for example, a political science essay. This aspect of power is usually excluded from legal reflection. In empirical research, however, it is of great importance.

E. The Empirical Study of Legal Doctrine
How can we go about studying doctrinal practices empirically and comparatively? As I have argued, the Sociology of doctrine is a field of research that has yet to take definitive shape. The aim of this section is to identify, from a bird's eye view, existing theoretical and methodological work which can be brought together in order to advance the state of the art. As my research into the history and present state of this research in the UK is still very much at the beginning, the following observations are limited to a description of some recent developments in theoretical and methodological approaches in the German literature-in order to be able to identify similar research in the UK and elsewhere later. 64

I. Theory
Traditional sociological theory has focused on observable human behavior and has regarded law as an epistemic object. Legal knowledge in this perspective consists of information, practices, discourses, et cetera, which are regarded, "known," and (re-)produced by actors as "legal." The 60 Id. acting persons-for example judges, lawyers, legal academics, clients, or citizens-approach the law with often antagonistic interests and world views that can be in some way empirically determined or are theoretically presumed.
Max Weber's work falls into this tradition and is still quite influential, both in the social sciences and in the law in Germany. This is not surprising because Weber was a lawyer himself who used concepts from legal doctrine 65 to analyze the law sociologically. Weber pointed out the societal embeddedness of the law with his concept of "legal thinking," which was not about legal ideas alone, but also how they developed in response to social and economic needs, institutional constraints and incentives, and self-interests of the legal profession. 66 Weber's ideal typical description of what continental, or more specifically, German, legal doctrine purported to do at the turn of the twentieth century is that "the jurist, taking for granted the empirical validity of the legal propositions, examines each of them and tries to determine its logically correct meaning in such a way that all of them can be combined in a system which is logically coherent, in other words, free from internal contradictions." 67 For him, this "rational" system of doctrine was the outcome of the monopolization of legal education at the universities. Weber contrasted this type of "legal thinking" with the situation in England, where the "empirical training in the law as a craft training" prevented such rationalization to take place. 68 At the same time, this form of legal thinking implies contrasting visions of the role of the judge-anonymous legal "automaton" in Germany, charismatic judge in the UK. 69 Taking into account the deficiencies of a work that is more than one hundred years old, 70 the basic tenets of Weberian thinking continue to inspire general theorizing and often provide a common ground for lawyers and social scientists. 71 However, few studies apply Weberian theory for actual empirical research. 72 In recent years, Pierre Bourdieu's work on law has become influential in German socio-legal studies. 73 Bourdieu builds on Weber's actor-centered and institutional analysis but adds the idea of the legal "field" in which individuals and groups with different "legal capital" and distinctive forms of "habitus" struggle for hegemony over the authoritative interpretation of the law. In his writings on law, which are exclusively concerned with the French case, the conflictual nature of the legal field is emphasized in a particularly strong manner: It is a matter of struggles over symbols and interpretations, but also over institutional hierarchies and financial resources. 65 For example, note his use of "formal" and "substantive" to categorize types of legal thinking in different religions and parts of the world. See WEBER, supra note 50, at 654. 66 Id. at 654-58. 67 Id. at 311. From the context, it becomes clear that Weber does not claim that the legal method would actually bring laws into a logically coherent system. For him, lawyers in the continental European legal act as if this were the case, which has an effect on how the law works. 68 Id. at 784. It is important to remember that "rational" in the Weberian sense is an analytical, not evaluative term. Bourdieu's concept of "habitus" is especially useful if we want to conceptualize doctrine as a social practice-meaning the sum of behaviors, attitudes, and ways of thinking that an individual has been socialized into as a part of a social group, such as lawyers, judges, professors, or bureaucrats. 74 Bourdieu is skeptical of the doctrinal habitus 75 but does not speak to the thesis of the indeterminacy of law. Instead, Bourdieusian insights are useful to identify social factors that affect the autonomy of legal discourse from within the legal field. 76 The most individualistic approach surveyed here is the research on Behavioral Law and Economics that has gained prominence in Germany in the last couple of years following developments in economics in the United States. 77 It is premised on the theoretical model of utility maximizing actors, but unlike the original rational choice model of the homo economicus with fixed preferences, it allows for corrections of that model, for example, via controlled experiments, or by using large legal datasets-which I will analyze in greater detail below. Even though the research in this tradition is empirical, it so far has remained largely unconnected to socio-legal studies, which has to do, inter alia, with the fact that this line of research is interested in empirical questions mainly to solve legal questions rather than advance social scientific theorizing. 78 Law and Economics has traditionally regarded itself as an alternative to doctrinal analysis. 79 Because there are many ways in which the production of legal doctrine can be analyzed from an economic perspective, even those skeptical of economic perspectives should not discount the heuristic value of these approaches. 80 Radically opposed to approaches that look at individuals and groups is the Systems Theory perspective developed by Niklas Luhmann and Gunther Teubner. 81 Such approaches understand law as an epistemic subject. From this perspective, law is a communicative system that creates its own reality, including the acting "persons," who appear only as "semantic artefacts" created by the system itself. System Theory views law as a self-referential system of communicative operations 82 that differ from other communications by using the binary distinction between "legal" and "illegal." 83 For Luhmann, Rechtsdogmatik in its specific German characteristic is "one of several functionally equivalent solutions" of how the legal system is controlling its operations. 84 Systems-theoretical legal analysis has often been criticized for taking tortuous detours to address the fact that "questions of interpretation are questions of power and sovereignty," 85 a problem that "Critical Systems Theory" aims to address. 86 System Theory is probably the best theory we have to describe the emergence of the precarious and, according to Luhmann, highly unlikely autonomy of law, via a process of functional differentiation. 87 However, as Matthias Mahlmann has argued, System Theory is not particularly well-suited to identify the specific social forces or purposeful interventions-for example, by moral entrepreneurs-that very often drive real legal development. 88

II. Methods
In German Sociology of law, different empirical methods have been used to look at what lawyers are doing. In the 1970s, Ekkehard Klausa called for an empirical "Sociology of Jurisprudence" and used survey research to gather information on law professors. 89 More influential was Rüdiger Lautmann's study from 1972, which engaged in covert participant observation to study how first-instance court judges actually decide cases. 90 After that, most work was theoretical and hermeneutic. It took roughly forty years before new empirical work in this tradition was produced, such as a study by Peter Stegmaier, who relied on interviews and overt participant observation to analyze how private and administrative judges deal with cases. 91 But it was not the Sociology of Law that was most productive in this respect. 92  Using survey research, interviews, or ethnographic methods 95 can produce valuable empirical data. One reason why these works are so rare is that applying these methods involves a lot of additional effort and time-sometimes also financial resources-usually more than is required when doing desk-based research, not to mention the fact that German lawyers do not receive training in empirical methods. The general reluctance by legal professionals to publicly reflect on the various non-legal influences on their craft has been very strong in Germany, 96 although this might be changing with new generations of increasingly interdisciplinary-minded legal scholars and practitioners. In many cases, however, only trained lawyers have access to, and can report from, what is going on inside the legal black box. 97 An alternative approach is to return the focus to doctrinal text production. Recent literature has taken up concepts from literary studies to differentiate the ways in which textual data can be approached. On the one hand, "close reading" pays attention to the meaning of individual texts, and traces the development, diffusion, and transformation of doctrinal ideas against the social context in which they exist. An example of this kind of research in German constitutional law history would be Thomas Henne's and Arne Riedlinger's edited volume on the Lüth Decision of the German Federal Constitutional Court, 98 which works out the historical context in which the doctrine of the "direct third-party effect" in German constitutional law was developed. Another example is Gunter Frieder's work on the competition between the Smend and Schmitt "schools" over doctrinal dominance in constitutional law scholarship in post-war Germany. 99 Recently, Verena Frick traced the internal struggles within the German Association of Constitutional Law Teachers and the influence of these debates on constitutional law from a political science perspective. 100 These works emphasize the importance of biographical detail, academic lineages, institutional competition, and historical events for the development of doctrinal thought. They call for the "historicization" of doctrine as opposed to the decontextualization and abstraction to which German legal thought tends. 101 On the other hand, "distant reading" digests a large number of texts by having algorithms "read" the texts. 102 Algorithmic reading of judicial or academic doctrinal texts is a newer branch of research into legal doctrine that differs from the traditional social scientific method of using texts as data with which to test hypotheses. 103 Another method for inferring causal relationships 95 using a large number of texts is network analysis, which has been used, inter alia, to uncover citation networks in the jurisprudence of apex courts. 104 A third often-used quantitative methodology is to use topic modeling algorithms, which have been defined as "statistical text mining or information retrieval methods used for uncovering the main themes underlying a collection of documents." 105 This, for example, is used to show how rules of procedure affect the material content of decisions of the German Constitutional Court. 106 Finally, I should mention recent efforts to bring together quantitative legal studies and legal linguistics, which will certainly have to be a part of a comparative study of doctrine. 107 These text-based quantitative methodologies have been almost exclusively applied to digital text collections of judicial decisions. Unlike most other forms of legal data, collections of judicial decisions can, in many cases, be freely downloaded. In contrast, the access to digitized forms of legal scholarship is, in the majority of cases, encumbered by corporate paywalls and publisher's copyright-not to mention the complication of the fragmented state of ownership over the documents. This is probably the reason why legal doctrinal scholarship has not yet been the subject of much quantitative research. As legal scholarship increasingly moves to open access publishing and historical doctrinal scholarship falls into the public domain, we can expect growing opportunities for research on legal doctrinal scholarship. Given the availability of doctrinal "big data," we will be able to trace the emergence and development of doctrinal figures, trace citation networks, and academic lineages, as well as pursue other research questions that have occupied qualitative research for a long time.

E. Conclusion and Outlook
I have presented some of the theoretical and methodological approaches in German research on law that can be brought to bear on the interdisciplinary study of doctrine. The existing variety of theories and methods provides multiple angles from which to choose and explain historical and contemporary data. Combined with similar efforts in the UK and elsewhere, there is great potential for the comparative analysis of doctrinal knowledge production.
In the literature that I have surveyed, we have seen a diverse set of research questions, which could be brought together and pushed forward in a systematic interdisciplinary and comparative research program. One of them has been the question: To what extent do judicially or academically produced doctrinal rules determine judicial decisions? This concerns the varying degrees to which scholarship influences judges in their decision-making and whether this influence is openly acknowledged or not. 108 However, it is important to ask what relationship exists between doctrinal practices and the character of the political regime in which it is embedded. 109 Another, more theoretical line of inquiry, has been to ask about the function of law, and therefore legal-doctrinal practices in society. 110 In what ways does doctrine support law's role as a tool of social control in the hands of the economically powerful, as scholars in the Marxian tradition have argued? 111 How does doctrine, as a practice, preserve inequalities in terms of, for example, gender and race? 112 And, on the contrary, in which cases can doctrinal practices be employed towards the aim of inducing progressive social change? 113 How does doctrine help sustain law's role as a medium of social integration envisioned by classical Sociology in the tradition of Durkheim and Weber? 114 Finally, what do the widely divergent doctrinal practices in different jurisdictions tell us about law's function of stabilizing normative expectations postulated by System Theory? 115 In addition, one can look at other theoretical perspectives that I have not mentioned. For example, it would be useful to connect the comparative Sociology of academic disciplines on one side, 116 with the comparative study of legal scholarship, and of socio-legal studies, on the other. In addition, further empirical research is needed to determine how processes of doctrinal argumentation and persuasion actually work in the different legal arenas given the solid evidence of various cognitive biases that affect the "rationality" of legal argumentation and decision-making. 117 This research would be crucial in covering the middle ground between the equally implausible, and largely abandoned, theoretical positions that maintain that doctrine either is the product of an internal "scientific" legal logic, or simply mirrors external influences-such as societal power relations, judges' ideological preferences, et cetera.
In German legal discourse, some argue that "through doctrinal work, objectification and value neutrality can and should be achieved." 118 Most empirical theorists are doubtful of earlier claims that legal doctrine is actually able "to transform value judgements into questions of knowledge and truth." 119 As we have seen, whereas earlier social science theorizing, in particular in the United States, was convinced that legal arguments mattered little in the decision-making of courts, empirical research in the meantime has "established the very important point that 110 doctrine does matter in future decisions." 120 How exactly this plays out in the interaction between courts, legal practitioners and the legal academy can be the subject of future interdisciplinary and comparative research. I have tried to show that doctrine, which many regard as arcane and/or boring by non-lawyers, is actually an interesting and important subject for comparative socio-legal research, and that it can elucidate some of the very marked legal-cultural differences between countries such as Germany and the UK.