(1)  Subject to this section and to section 6 , for all the purposes of the laws of the State –

(a) a person who, on or after the appointed day, attains the age of 18 years shall be deemed to attain full age and full capacity on attaining that age; and

(b) a person who, on the appointed day, is of or over the age of 18 years but under the age of 21 years shall be deemed to have attained full age and full capacity on that day.

(2)  Subsection (1) applies and has effect, in the absence of a definition or of an indication of a contrary intention, for the purposes of the construction of the expressions "majority", "full age", "adult", "full capacity", "sui juris", and similar expressions, and the expressions "infant", "infancy", "minor", "minority", and similar expressions in –

(a) an enactment, whether passed or made before, on, or after the appointed day; and

(b) an instrument executed or made on or after that day.

(3)  This section does not affect a reference in an enactment or instrument to an age expressed in years.

(4)  This section does not affect any deficiency of juristic competence or capacity that is attributable to insanity, or mental infirmity, or any other factor distinct from age.