System and method for secure, policy-based access control for mobile computing devices

A method for selecting a policy instruction for evaluation in a hierarchical policy instruction set in a policy-based decision-making system, wherein the hierarchical policy instruction set includes, at least one priority ordering, at least one conditional clause, and at least one decision parameter, the steps comprising:

• reading a specific value set;
• applying the specific value set to each policy instruction to compute a discriminant expression associated with each policy instruction that determines when said policy instruction is a candidate for selection based on the specific value set;
• selecting candidate policy instructions, wherein the candidate policy instructions are those policy instructions whose discriminant expressions evaluate to a non-false value;
• in order of the priority ordering, evaluating the conditional clauses for each candidate policy instruction, selecting the first candidate policy instruction for which all associated conditional clauses evaluate to true;
• where there exists exactly one selected policy instruction, return the decision parameters defined in the selected policy instruction;
• and
• and
• where there exist no selected policy instruction, return a default decision.