In the United Kingdom, individuals requiring inpatient care for mental health purposes can be admitted to hospital with their consent as informal patients, or formally through procedure(s) prescribed by law. There are, however, instances where individuals otherwise referred to as informal patients are on admission without their consent or in circumstances that amount to deprivation of their liberty as defined by the United Kingdom Supreme Court and without recourse to lawful procedures by their clinical team as stipulated by the European Convention on Human Rights. Such instances might be without the awareness of the individuals or their clinical teams or the clinical teams might be unclear as to which statute applies to patient care. This paper has been written to help clinicians define the legal status of patients at the point of admission, during their stay on the inpatient unit and the statute(s) that apply to different in-patient situations.