Nursing practice no longer relies on tradition or ritual; instead, it is based on research and empirical evidence. The emphasis on evidence-based nursing, as well as standardization of nursing practice, has resulted in the production of policies, protocols and guidelines aimed at directing numerous aspects of nursing care. The aim of this study was to explore the relationship between these documents and actual nursing practice. To this end, this descriptive study employed a case study approach to examine the experiences of nurses in an Irish intensive care unit with a protocol on endotracheal tube suctioning. Focus group interviews of 17 nurses in six focus groups provided a significant insight into the experiences of these nurses in relation to policies, protocols and guidelines. Analysis of the data afforded some highly relevant findings, including the fact that nurses adapt clinical protocols as they see fit, thus demonstrating the importance that they place on their own professional judgement and autonomy.