From a modern heart pacemaker to a computer-controlled jet engine in a civilian flight or an air fighter, Safety-critical systems – i.e. those systems whose failure could result in loss of life – have become more common and powerful than ever. Needless to say, the verification process of such systems requires higher rigour when compared to the verification process of usual commercial software systems, in order to guarantee the critical aspects of the systems, e.g. safety and security. The rigorous verification process, however, can dramatically increase the cost of the software development process. This book extends the Compliance Notation – a unified framework where both formal and informal techniques can be employed in sequential software development –and provide a novel approach to the verification of concurrent safety critical systems. The viability of the new approach is illustrated using a real example form the safety-critical industry, namely, a robot-operated production cell. Finally, the book draws conclusions on the proposed approach and discusses future research directions.