T.C.A 33-6-401 (as amended by Public Acts 2000, Chapter 947, section 1) permits for emergency detention: IF AND ONLY IF (1) a person has a mental illness or serious emotional disturbance, AND (2) the person poses an immediate substantial likelihood of serious harm under § 33-6-501 because of the mental illness or serious emotional disturbance, THEN (3) the person may be detained under § 33-6-402 to obtain examination for certification of need for care and treatment.

T.C.A. 33-6-402 (as amended by Public Acts 2000, Chapter 947, Section 1) states that if an officer authorized to make arrests in the state, a licensed physician, a psychologist authorized under § 33-6-427(a), or a professional designated by the commissioner under § 33-6-427(b) has reason to believe that a person is subject to detention under § 33-6-401, then the officer, physician, psychologist, or designated professional may take the person into custody without a civil order or warrant for immediate examination under § 33-6-404 for certification of need for care and treatment.

T.C.A. 33-6-425 (as amended by Public Acts 2000, Chapter 947, Section 1) states that no defendant shall be detained at a jail or other custodial facility for the detention of persons charged with or convicted of criminal offenses, unless the defendant is under arrest for the commission of a crime.