In this paper we present the motivation, use cases, design principles, abstract syntax, and initial core of LegalRuleML. The LegalRuleMLcore is sufficiently rich for expressing legal sources, time, defeasibility, and deontic operators. An example is provided. LegalRuleMLis compared to related work. Categories and Subject Descriptors CR number [category]: sub-category—optional subject descriptor General Terms Languages, Standardization Keywords LegalRuleML