This article explores the main elements of the Mental Capacity Act 2005 and the implications for nurses. Many vulnerable adults have impaired capacity, and it is vital that nurses are confident in understanding when and how to assess an individual’s capacity. Nurses should be supported and given training to ensure they can apply the principles of the Mental Capacity Act 2005 to practice. It is also important that nurses have a good understanding of the deprivation of liberty safeguards and can identify when their interventions may deprive patients of their liberty, ensuring that these are only undertaken legally.