This document discusses the Lynx project which aims to build a legal knowledge graph to support smart compliance services across multilingual Europe. It faces challenges with interoperability across different legal sources. Three pilot contracts are described relating to contract processing, geothermal industry standards, and labor law harmonization. The legal knowledge graph aims to link various legal data sources like directives, national legislation, regulations, case law and standards. It discusses where the Lynx legal knowledge graph fits relative to other legal information systems and knowledge graphs. A minimal meta-model is proposed to define a common structure for representing different types of legal information and sources.