The majority of legal knowledge based systems (LKBS) in commercial use are rule based and target domains of law characterized by large and complex statutes where modelling discretion is not a central concern. Furthermore, to date, few LKBS execute on the World Wide Web. Despite this, LKBS designed for a web environment can make law more universally accessible and transparent. Tools required to facilitate the development of web based systems include a web based expert system shell, conceptual tools that allow for the identification of appropriate domains for web implementation, modeling tools for discretionary domains and architectures for virtual discourse. We present a shell called WebShell that uses two knowledge modelling techniques; decision trees for procedural type tasks and argument trees for tasks that are more discretionary. Rather than translate decision tree knowledge into rules for a conventional inference engine, we map the decision trees into sets we call sequence transition networks. These sets can readily be stored in relational database format in a way that simplifies the inference engine design. Although WebShell facilitates the deployment of LKBS in a web environment, it does not encourage negotiation and virtual discourse. An argumentation shell program, Argument Developer is presented that encourages participants in a virtual discursive community to understand each other's perspectives and reach decisions by consensus. Copyright 2001 ACM.