We are delighted to present the proceedings volume of the 31st International Conference on Legal Knowledge and Information Systems (JURIX 2018). For more than three decades, JURIX has organized an annual international conference for academics and practitioners, recently also including demos and a hackathon. The intention is to create a virtuous exchange of knowledge between theoretical research and applications in concrete legal use-cases. JURIX is also a good community where different skills work together to advance research by way of cross-fertilisation between law and computer technologies.

The JURIX conferences have been held under the auspices of the Dutch Foundation for Legal Knowledge Based Systems (www.jurix.nl). It has been hosted in a variety of European locations, extending the borders of its action and becoming an international conference in virtue of the the various nationalities of its participants and attendees.

The 2018 edition of JURIX, which runs from December 12 to 14, is hosted by the Faculty of Law and the Department of Artificial Intelligence in the Bernoulli Institute of Mathematics, Computer Science and Artificial Intelligence of the Faculty of Science and Engineering of the University of Groningen. JURIX 2018 is organised in cooperation with the Dutch Research School for Information and Knowledge Systems (SIKS). Special thanks go to Jeanne Mifsud Bonnici, Henry Prakken, and Bart Verheij and to their team for inviting us, hosting the event, and making this conference possible (http://jurix2018.ai.rug.nl).

For this edition we have received 72 submissions by 221 authors from 26 countries; 17 of these submissions were selected for publication as full papers (10 pages each) and 11 as short papers (five pages each), for a total of 28 presentations. We were inclusive in making our selection, but the competition stiff and the submissions were put through a rigorous review process with an acceptance rate of 38.8%. Borderline submissions, including those that received widely divergent marks, were accepted as short papers only.

The accepted papers have been grouped under six headings: (i) Machine Learning for the Legal Domain, a session presenting different methodologies and theoretical models applied to legislative texts and case-law (seven full papers and two short papers); (ii) Legal Reasoning and Argumentation, a session that ranges from theoretical aspects and demonstrations (three full papers and four short papers); (iii) Legal Knowledge Extraction, a session that presents natural-language processing of text for detecting terms, principles, concepts, evidence, rules, and named entities, and also speech in chatbots (two full papers and two short papers); (iv) Legal Knowledge Retrieval, a session focused on the answer-and-query approach (two full papers); (v) Legal Knowledge Modelling and Visualization, devoted to Semantic Web techniques, such as legal thesauri and ontologies (three full papers and one short paper); and (vi) Legal Blockchain, a session that has been growing in significance for several years in the workshop area, and now gains entry into the main conference (two full papers, one short paper).

This year we are honoured to have Marie-Francine Moens, full professor in the Department of Computer Science at Katholieke Universiteit Leuven, director of the Language Intelligence and Information Retrieval (LIIR) Research Lab, member of the Human Computer Interaction Group, and head of the Informatics section. She is a well-known researcher who experiments with novel methods for automated content recognition in text and multimedia, using statistical machine learning and exploiting insights from linguistic and cognitive theory. She has also successfully applied these techniques to the legal domain.

Also noteworthy is that the ethical aspects are increasingly relevant in big data and AI applications. For this reason we have asked to Jeroen van den Hoven to provide us with an overview of the ethical issues that emerge in connection with the use of emerging technologies. He is full professor of Ethics and Technology at the Delft University of Technology and editor in chief of Ethics and Information Technology.

We are very grateful to them for having accepted our invitation and for their interesting and inspiring talks.

Since 2013, JURIX has also hosted the Doctoral Consortium, now in its sixth edition. This initiative aims to attract and promote Ph.D. researchers in the area of AI & Law so as to enrich the community with original and fresh contributions. Many thanks are owed to Pompeu Casanovas, Ugo Pagallo, and Giovanni Sartor for organising the consortium this year, helped by other senior scholars.

As the previous editions, also this year the conference is growing richer with six co-located workshops. With long-running workshop like AICOL and LDA, we are continuing the TeReCom event and are hosting four new initiatives: XAILA, Legal Design, ManyLaws, and Legal Data Analytic Hackathon.

The Workshop on Artificial Intelligence and the Complexity of Legal Systems (AICOL), now in its tenth edition, is a stable event whose aim is to cut across multiple disciplines so as to examine the complexity of legal systems. The LDA workshop on Legal Data Analysis of the Central European Institute of Legal Informatics (CEILI), at its fifth edition, is devoted to the representation and analysis of legal data and documents, and to reasoning on such data and documents, using corpora and information systems.

The second edition of the Workshop on Technologies for Regulatory Compliance provides a forum for discussion of research on technologies for regulatory compliance on the basis of Semantic Web and Artificial Intelligence techniques. This workshop is supported by the LYNX European project: Building the Legal Knowledge Graph for Smart Compliance Services in Multilingual Europe (http://lynx-project.eu/).

The first-ever EXplainable AI in Law (XAILA) workshop aims to investigate the intersection of law and AI in order to provide a conceptual framework for ethical concepts and values in AI systems.

The first-ever ManyLaws workshop focuses on the semantic annotation of Big Legal Open Data, easily searchable and exploitable, on the basis of text-mining tools and algorithms offered through proper visualization techniques.

In this regard the Legal Design workshop integrates the previous ones with interdisciplinary and human-centered design principles to prevent or solve legal problems.

This year JURIX is also hosting a new challenge with the the Legal Data Analytics Hackathon (LeDAH), aiming to create applications and concrete projects using data-analytics methods applied to legal documents and data, with a specific focus on bringing out cognitive biases and providing visualization to support the transparency of legal information.

The JURIX 2018 conference was supported by IOS Press, BNKVI (the Benelux Association for Artificial Intelligence), and the OASIS LegalXML Steering Committee: many thanks to them, whose help made it possible to organise this event, and whose technical support contributed to attracting many participants from around the world.

Finally, we want to thank the program committee and sub-reviewers for reviewing the submissions with a professional and scientific attitude, enriched by active discussions that have ensured a fair reviewing process; the 221 authors who have submitted papers; the workshop organisers, who have enhanced the JURIX conference with emerging topics; the hackathon organizers for the applicative approach; and, finally, the members of the JURIX Steering and Executive Committees for supporting the conference year after year.

Monica Palmirani

CIRSFID, University of Bologna, Italy