Mental Disorder Definition:

Also known as mental illness or mental disease.

In the context of their DSM-IV catalogue of mental disorders, the American Psychiatric Association defines a mental disorder as follows:

"A clinically significant behavioral or psychological syndrome or pattern that occurs in an individual and that is associated with present distress or disability or with a significantly increased risk of suffering death, pain, disability or an important loss of freedom."

In the context of mental health and the necessity of medical assistance to those suffering from mental disorders, statutes generally define mental disorders similar to this example from the Canadian province of New Brunswick, circa 2010:

"Mental disorder means a substantial disorder of thought, mood, perception, orientation or memory that grossly impairs a person’s behaviour, judgment, capacity to recognize reality, or ability to meet the ordinary demands of life."

Compare with the British Columbia statutory definition:

"Person with a mental disorder means a person who has a disorder of the mind that requires treatment and seriously impairs the person's ability to react appropriately to the person's environment, or to associate with others."

In Vergara, Justice Wright of the Court of Appeals of Nebraska wrote:

"[A] person with a mental disorder is one who suffers from a condition of mental derangement which actually prevents the sufferer from understanding his or her legal rights or from instituting legal action."

French: trouble mental.

REFERENCES:

• American Psychiatric Association, Diagnostic and Statistical Manual of Mental Disorders, 4th ed. (Washington, DC: American Psychiatric Association, 2000)
• Duhaime, Lloyd, Duhaime's Legal Dictionary
• Duhaime, Lloyd, Duhaime's Legal Citations & Abbreviations
• Mental Health Act, R.S.B.C. 1996, c. 288
• Mental Health Services Act, S.N.B. 1997, c. M-10.2
• Vergara v Lopez-Vasquez, 510 N.W. 2d 550 (1993)