Legal Complexity Science

Social, economic and political complexity have manifested in increasing levels of legal complexity. While legal systems have to find ways to handle this increase, technology and data science can help further the understanding of their performance and provide them with much-needed tools.

The legal data science project follows a quantitative approach in the analysis of law. Its activities fall into three categories: the creation of data sets, their analysis and the communication and application of their results. The theoretical foundation is provided by complexity science, as the legal system is understood as a complex adaptive system (CAS). As such, its properties can be measured with methods from computer science, physics and mathematics, such as network science, text analytics and data mining. Developing these methods and applying them to various datasets is at the core of the project’s activities. However, many of these datasets need to be built, enriched, documented and open-sourced before any analysis can be conducted. As a last step, the resulting research needs to be communicated to other quantitative and normative legal scholars and turned into actionable steps for policymakers and practitioners.

The goal of this project is an enhanced and robust understanding of the legal system and its dynamics. This is achieved through publications in interdisciplinary, peer-reviewed general scientific journals and presentations at both research and practitioner conferences.

Complex Societies and the Growth of the Law

While a large number of informal factors influence how people interact, modern societies rely upon law as a primary mechanism for formally controlling human behavior. The impact of legal rules on societal development depends on the interplay between two types of actors: the people who create the rules and the people to which the rules potentially apply. We hypothesise that an increasingly diverse and interconnected society might create increasingly diverse and interconnected rules, and assert that legal networks provide a useful lens through which to observe the interaction between law and society. To evaluate these propositions, we present a novel and generalizable model of statutory materials as multidimensional, time-evolving document networks. Applying this model to the federal legislation of the United States and Germany, we find impressive expansion in the size and complexity of laws over the past two and a half decades. We investigate the sources of this development using methods from network science and natural language processing. To allow for cross-country comparisons over time, we algorithmically reorganise the legislative materials of the United States and Germany into cluster families that reflect legal topics. This reorganisation reveals that the main driver behind the growth of the law in both jurisdictions is the expansion of the welfare state, backed by an expansion of the tax state.

Measuring Law over Time

How do complex social systems evolve in the modern world? This question lies at the heart of social physics, and network analysis has proven critical in providing answers to it. In recent years, network analysis has also been used to gain a quantitative understanding of law as a complex adaptive system, but most research has focused on legal documents of a single type, and there exists no unified framework for quantitative legal document analysis using network analytical tools. Against this background, we present a comprehensive framework for analyzing legal documents as multi-dimensional, dynamic document networks. We demonstrate the utility of this framework by applying it to an original dataset of statutes and regulations from two different countries, the United States and Germany, spanning more than twenty years (1998–2019). Our framework provides tools for assessing the size and connectivity of the legal system as viewed through the lens of specific document collections as well as for tracking the evolution of individual legal documents over time. Implementing the framework for our dataset, we find that at the federal level, the American legal system is increasingly dominated by regulations, whereas the German legal system remains governed by statutes. This holds regardless of whether we measure the systems at the macro, the meso, or the micro level.


Daniel Katz

  • CodeX Affiliated Faculty
  • Professor of Law, Illinois Tech – Chicago Kent College
  • Director, The Law Lab, Illinois Tech

The descriptions of current and past projects of CodeX non-residential fellows are provided to illustrate the kind of work our non-residential fellows are carrying out. These projects are listed here for informational purposes only and are not endorsed by CodeX, Stanford Law School, or Stanford University.