ACORD has some ontologies used in the insurance industry
Stanford Legal Design Lab's LIST: Legal Issues Taxonomy
SALI's Legal Matter Specification Standard
National Subject Matter Index: Taxonomy directed at American legal aid providers
Legal Taxonomy Syllabus
NCSC Open Court Data Standards
Schema4i.org - Schema for insurances
RuleML: Unifying system of rule language families
RIF: W3C standard for rules
LKIF
LegalRuleML
SWRL: A combination of subsets of OWL-DL and RuleML
Normative Requirements Vocabulary (NVR): OWL ontology for legal norms (Inria)
ODRL
LDR
See Rules and Norms: Requirements for Rule Interchange Languages in the Legal Domain
Akoma Ntoso legislative XML standard
MetaLex XML
Norme in Rete
X2RL: A "semantic" (rather than "syntactic") machine-readable format under development at the Mercatus Center
Australia's National Legal Assistance Data Standards Manual
Clicklaw's common web metrics