8.—A person shall be disqualified for jury service if on conviction of an offence in any part of Ireland—

( a ) he has at any time been sentenced to imprisonment or penal servitude for life or for a term of five years or more or to detention under section 103 of the Children Act, 1908, or under the corresponding law of Northern Ireland, or

( b ) he has at any time in the last ten years—

(i) served any part of a sentence of imprisonment or penal servitude, being, in the case of imprisonment, a sentence for a term of at least three months, or

(ii) served any part of a sentence of detention in Saint Patrick's Institution or in a corresponding institution in Northern Ireland, being a sentence for a term of at least three months.