(1)For references in the [1959 c. 72.] Mental Health Act 1959 (" the principal Act") to subnormality or severe subnormality there shall be substituted references to mental impairment or severe mental impairment within the meaning of section 4 of that Act as amended by subsection (2) below.
(2)For subsections (2) and (3) of the said section 4 there shall be substituted—
“(2)In this Act ' severe mental impairment' means a state of arrested or incomplete development of mind which includes severe impairment of intelligence and social functioning and is associated with abnormally aggressive or seriously irresponsible conduct on the part of the person concerned.
(3)In this Act 'mental impairment' means a state of arrested or incomplete development of mind (not amounting to severe mental impairment) which includes significant impairment of intelligence and social functioning and is associated with abnormally aggressive or seriously irresponsible conduct on the part of the person concerned.”
(1)For subsection (4) of section 4 of the principal Act (definition of " psychopathic disorder ") there shall be substituted—
“(4)In this Act' psychopathic disorder' means a persistent disorder or disability of mind (whether or not including significant impairment of intelligence) which results in abnormally aggressive or seriously irresponsible conduct on the part of the person concerned.”
(2)In subsection (5) of that section (person not to be treated as suffering from mental disorder by reason only of promiscuity or other immoral conduct) after the words " or other immoral conduct " there shall be inserted the words " , sexual deviancy or dependence on alcohol or drugs. "