Marx’s discussions of law have long made jurists anxious. His relegation of law, along with art and philosophy, to the realm of ideology , his reference to law as a “mirror” , his insistence that “legal relations arise from economic ones” –taken together, these claims not only threaten to unsettle flattering narratives that put lawyers on the side of social progress, but suggest what some would take to be worse: that our work is, in historical terms, irrelevant.
Putting too much weight on these isolated remarks is a mistake. In Capital, Marx considers the functioning of law in depth.  Marxist scholarship has developed a thick body of theory on the relationship between historical materialism, class conflict, and the operation of the state–including law. And Marxist scholars would generally spurn the notion of a strict dichotomy that places law in an ideological superstructure sitting atop a wholly material base.
Moreover, it was largely legal scholars sympathetic to the Marxist tradition–notably Morton Horwitz, E. P. Thompson, and Karl Klare–who helped clarify an important and previously overlooked aspect of law’s relationship with social relations. Beyond acting as a tool of ruling class domination or reflecting the structure of social relations, law helps to constitute and materialize those relations. It is part of the fabric by which those relations are understood, circulated, and maintained. As history lurches forward, law is one place where the rubber meets the road.
In the rush to seize a moment of relevance for law, however, legal scholarship has overreached, inverting earlier fallacies and advancing a reading of “the constitutive” that overestimates the work that law does. The error is rooted in an illogical jump, from the observation that many salient categories of social life are also legal concepts to a conclusion that those categories are “fundamentally” legal.
Far from occasional bluster, such overreach is typical of scholarship seeking to critically examine the substantive relationship between legal discourse and the world. Take Robert Gordon’s classic “Critical Legal Histories”. Against an array of scholarly traditions that treat law as ancillary to a real world made up of basic elements that exist independently of law, Gordon argued that
“in practice, it is just about impossible to describe any set of ‘basic’ social practices without describing the legal relations among the people involved–legal relations that don’t simply condition how the people relate to each other but to an important extent define the constitutive terms of the relationship, relations such as lord and peasant, master and slave, employer and employee, ratepayer and utility, and taxpayer and municipality. For instance, among the first words one might use to identify the various people in an office would likely be words connoting legal status: ‘That’s the owner over there.’ ‘She’s a partner; he’s a senior associate; that means an associate with tenure.’ ‘That’s a contractor who’s come in to do repairs.’ ‘That’s a temp they sent over from Manpower.’ This seems an obvious point, but if it’s correct how can one square it with the standard view of law as peripheral to ‘real’ social relations? Could one, for example, seriously assert that ‘the law of slavery has tended to play only a marginal role in the administration of slave societies’? Slavery is a legal relationship: It is precisely the slave’s bundle of jural rights (or rather lack of them) and duties vis-à-vis others (he can’t leave, he can’t inherit, he has restricted rights of ownership, he can’t insist on his family being together as a unit, etc.) that makes him a slave. Change the bundle significantly and you have to call him something else. And how could one say something like ‘medieval law bolstered (or undermined) the structure of feudal society’? Again, a particular (though concededly in this case very hazily defined) set of legal relations composes what we tend to call feudal society. If those relations change (commutation of in-kind service to money rents, ousting of seignorial jurisdiction to punish offenses, etc.) we speak not simply of changes in ‘the legal rules regulating feudal institutions’, but of the decline of feudalism itself.” 
Law had a role in establishing the boundaries and limits of the mays, musts, and mustn’ts of relationships between slaves and other social classes; in continually reproducing “slave” as a socially understandable and politically legitimate category; in policing the cognitive content of slave and non-slave, and thus in maintaining the distinction between them; through all these effects, in perpetuating a slave society. But it is a step too far to say that “slavery is a legal relationship”, as if it were only a legal relationship. Though law may have made slavery possible as an institution, necessary causes are not sufficient causes. They are certainly not essences. Gordon wanted us to be careful about hypostasizing a strict separation of law and society; in practice, he offered a vision of society in which law occupies the entire field.
Thirty years of making this point seems not to have allowed us to get it right. Consider a recent articulation, once again using a vulgarized Marxism as the foil:
“In the first sentence of the opening chapter of the Communist Manifesto of 1848, Marx and Engels declared: ‘The history of all hitherto existing society is the history of class struggles.’ But after forty years had elapsed, Engels felt obliged to define the two main classes of modern capitalism, the bourgeoisie and the proletariat. To the 1888 English edition he added a note:
By bourgeoisie is meant the class of modern capitalists, owners of the means of social production and employers of wage labour. By proletariat, the class of modern wage labourers who, having no means of production of their own, are reduced to selling their labour power in order to live.
When it came to defining these crucial classes, Engels was obliged to refer to concepts such as ownership, employment of waged laborers, and the selling of labor power. None of these terms can be defined adequately without reference to law and legal ideas. Ownership–in the fullest sense–implies legal rights, enforced by recognized contract and the legal powers of the state. The employment contract is a specific legal form, differing from a contract for sales or services. Selling implies the legal transfer of property rights, on a temporary or permanent basis. The selling of labor power involves the legal transfer of limited rights of authority over the laborer and the use of her capacities toward contracted purposes. Law appears in the definitions of social classes which are regarded as fundamental. So law too must be at the foundation.” 
It is surely correct that the legal life of ownership, or of contract, employment, or marriage–or really any of the myriad concepts that exist in both law and the vernacular–contributes to the specific shape and material substance of that concept as a socially experienced category. Here Simon Deakin and his collaborators claim that ownership implies legal rights; that selling implies a legal transfer; that selling of labour-power involves the legal transfer of authority. But there is a far wider gap than they seem to allow between the proposition that these concepts are implicated and entangled with law and the proposition that law is “at their foundation”.
One odd aspect of the literature on economic performativity is that it engages infrequently with law and legal institutions. Muniesa’s The Provoked Economy considers how economic reality is provoked–shaped, reshaped, made to appear, made to respond–by the description of financial products by an investment bank, focus group outputs, the stylized case studies used in business education at Harvard, and the proliferation of performance indicators. MacKenzie’s An Engine, Not a Camera deals with how technologies, especially the algorithms that work to discover stock prices, may give reality to financial ideas; his Material Markets deals, among other things, with the role of accounting in substantiating “profits”, and of economics in shaping carbon markets. Callon’s seminal collection on “the laws of the markets” contains no contribution that deals with the role of law.  Indeed, none of these key texts engages with law’s role in making any of these categories.
It seems odd at first that those who have studied the contributions of economics or accounting or algorithms to the realization and materialization of the social phenomena they are supposed to help us understand would devote so little attention to law. But it becomes less surprising once we observe how much legal scholarship in its turn ignores the role of these non-legal practices in constituting most salient social categories. 
Legal scholars say “these words have a legal definition” and take that as proof positive that their meaning and significance is legal–that is, legal all the way down. (Part of the confusion may arise from a folk epistemology that supposes the meaning or significance of a concept can be captured by a definition.) We cannot understand how “capital” or “profit” work as part of the apparatus that orders our economic life without attending to how they are used in legal texts, and by legal institutions and legal actors. Granted. But it is a grave error to think that the existence of legal usages nullifies the existence of other meanings; even more grave to think that a legal definition might exhaust the social significance of those concepts. Accounting standards, software, spreadsheets, practical dependence on lessons learned in Econ 101–these too, and not just law, gives ownership its meaning, its significance, its substance.
And this glaring gap in legal accounts of the constitutive is only one part of the story.
The employee who undertakes a harmful, wasteful, or humiliating task because her boss tells her to do so may only feel coerced because she lives in a society where the apparatus of the state vindicates the rights of bosses to give orders. But the boss’ instruction, his expectation that it will be obeyed, her sense that she should obey, her fear if she refuses, the consequences if she does–these are incidents of a subordinate relationship that exists through much more than law. Like other categories described as legal, what an employee is “in the fullest sense” lives in the variety of understandings that the relevant individuals have of that concept, in the practices informed by those understandings, and in what emerges from interactions and conflicts between those practices. Those understandings and practices may be informed by law, and by other rationalized, institutionalized intellectual practices, but also by the norms reproduced by popular culture and familiar anecdote.
Father, profit, employee, corporation, capital, wife: there are important questions about the role of law (qua institutionalized, rationalized form of state power) in giving such categories and concepts social substance. There are important and even more difficult questions about the relationship among the meaning the legal system assigns to these categories, the understandings people rely on in everyday usage, and how practices organized around those concepts actually function. I leave aside here whether Marx’s discussions of law can be stitched together so as to yield a compelling account of law’s contribution to the constitution of institutions, relations of production, or class relations. I hold my peace, too, on whether it is analytically or politically fruitful to frame social relations as primarily material, even while acknowledging the cognitive-bureaucratic-technical practices sustaining and grounding those relations. But these issues cannot be investigated–the question cannot even be asked–if we cling to the narcissism that the use of concepts by lawyers and judges is rubber, road, and the turn of the wheel, entire.
Acknowledgments: Thanks to Umut Özsu and Genevieve Painter for feedback on earlier drafts.
 Karl Marx, A Contribution to the Critique of Political Economy (New York: International Publishers, 1970 ), 12.
 Karl Marx, Capital: A Critique of Political Economy, vol. 1, trans. Ben Fowkes (Harmondsworth: Penguin, 1976 ), 178.
 Karl Marx, Critique of the Gotha Program (New York: International Publishers, 1933 ), 20.
 Marx, Capital, vol. 1, ch. 10.
 E. P. Thompson, Whigs and Hunters: The Origin of the Black Act (New York: Pantheon, 1975); Karl Klare, “Law-Making as Praxis”, 40 (1979) Telos 123; Morton J. Horwitz, The Transformation of American Law, 1870–1960: The Crisis of Legal Orthodoxy (Oxford: Oxford University Press, 1992).
 Robert W. Gordon, “Critical Legal Histories”, 36 (1984) Stanford Law Review 57, 103–4.
 Simon Deakin et al., “Legal Institutionalism: Capitalism and the Constitutive Role of Law”, 45 (2017) Journal of Comparative Economics 188, 191.
 Michel Callon (ed.), The Laws of the Markets (Oxford: Blackwell, 1998); Fabian Muniesa, The Provoked Economy: Economic Reality and the Performative Turn (London: Routledge, 2014); Donald MacKenzie, An Engine, Not a Camera: How Financial Models Shape Markets (Cambridge: MIT Press, 2006); Donald MacKenzie, Material Markets: How Economic Agents Are Constructed (Oxford: Oxford University Press, 2009)
 One early exception is Jonathan Simon, “The Ideological Effects of Actuarial Practices”, 22 (1988) Law and Society Review 771. Legal anthropologists today seem least afflicted: see, e.g., Annelise Riles, Collateral Knowledge: Legal Reasoning in the Global Financial Markets (Chicago: University of Chicago Press, 2011).
Liam McHugh-Russell is a doctoral candidate in law at the European University Institute.