Abstract: A method and system for checking whether customer orders for transactions of financial instruments conform to business logic rules. Executable rule files are created and stored in a repository. New executable rule files can be created by scripting the new business logic rules in a script file which is converted into a corresponding source code file written in a computer programming language. The source code file is compiled to create an individual executable rule file. A rule selection repository contains identification of groups of selected executable rule files. The invention determines the category of the customer order and reads, from the rule selection repository, a group of executable rule files that correspond to the identified category of the customer order. The selected executable rule files are executed to check the conformance of the customer order. Execution results are stored in a status repository for subsequent retrieval and analysis.