A more thorough explanation:

The term "non compos mentis" means "not of sound mind" in Latin. In legal terms, it refers to any degree of mental incompetency recognized by the law. It is used to describe a person who is unable to manage their affairs or comprehend their legal rights or liabilities due to a severe impairment of their mental faculties.

For example, a person suffering from dementia or a severe mental illness may be considered non compos mentis. However, mere emotional instability or depression does not qualify as non compos mentis.

Another example is a person who has suffered a traumatic brain injury and is unable to make decisions or understand their legal rights. In such cases, the court may appoint a guardian or conservator to manage their affairs.

Overall, non compos mentis is a legal term used to describe a person's mental state and their ability to manage their affairs and comprehend their legal rights. It is an important concept in the legal system to ensure that vulnerable individuals are protected and their interests are safeguarded.