Legal contracts specify requirements for business transactions. As any other requirements specification, contracts may contain errors and violate properties expected by contracting parties. Symboleo was recently proposed as a formal specification language for legal contracts. This paper presents SymboleoPC, a tool for analyzing Symboleo contracts using model checking. It highlights the architecture, implementation and testing of the tool, as well as a scalability evaluation with respect to the size of contracts and properties to be checked through a series of experiments. The results suggest that SymboleoPC can be usefully applied to the analysis of formal specifications of contracts with real-life sizes and structures.

Smart contracts (SCs) are software systems that monitor and control the execution of legal contracts to ensure compliance with the contracts' terms and conditions. They often exploit Internet-of-Things technologies to support their monitoring functions, and blockchain technology to ensure the integrity of their data. Ethereum and business blockchain platforms, such as Hyperledger Fabric, are popular choices for SC development. However, there is a gap in the knowledge of SCs between developers and legal experts. Symboleo is a formal specification language for legal contracts that was introduced to address this issue. Symboleo specifications directly encode legal concepts such as parties, obligations, and powers. In this paper, we propose a tool-supported method for translating Symboleo specifications into smart contracts. We have extended the current Symboleo IDE, implemented the ontology and semantics of Symboleo into a reusable library, and developed the Symboleo2SC tool to generate Hyperledger Fabric code exploiting this library. Symboleo2SC was evaluated with three sample contracts. The results shows that legal contract specifications in Symboleo can be fully converted to SCs for monitoring purposes. Moreover, Symboleo2SC helps simplify the SC development process, saves development effort, and helps reduce risks of coding errors.