In determining for the purposes of this Part whether the dismissal of an employee is fair or unfair, it is for the employer to show—
the reason (or, if more than one, the principal reason) for the dismissal, and
that it is either a reason falling within subsection (2) or some other substantial reason of a kind such as to justify the dismissal of an employee holding the position which the employee held.
A reason falls within this subsection if it—
relates to the capability or qualifications of the employee for performing work of the kind which he was employed by the employer to do,
relates to the conduct of the employee,
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is that the employee was redundant, or
is that the employee could not continue to work in the position which he held without contravention (either on his part or on that of his employer) of a duty or restriction imposed by or under an enactment.
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In subsection (2)(a)—
"capability", in relation to an employee, means his capability assessed by reference to skill, aptitude, health or any other physical or mental quality, and
"qualifications", in relation to an employee, means any degree, diploma or other academic, technical or professional qualification relevant to the position which he held.
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Where the employer has fulfilled the requirements of subsection (1), the determination of the question whether the dismissal is fair or unfair (having regard to the reason shown by the employer)—
depends on whether in the circumstances (including the size and administrative resources of the employer's undertaking) the employer acted reasonably or unreasonably in treating it as a sufficient reason for dismissing the employee, and
shall be determined in accordance with equity and the substantial merits of the case.
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Subsection (4)is subject to—
sections 98A to 107 of this Act, and
sections 152, 153 , 238 and 238A of the Trade Union and Labour Relations (Consolidation) Act 1992 (dismissal on ground of trade union membership or activities or in connection with industrial action).