The EU Ruling was that it is not discriminatory within the meaning of EU legislation to treat a pregnancy-related illness the same as any other illness.
The McKenna case claimed discrimination contrary to Directive 76/207. The Court found that a sick leave scheme that treats female workers suffering from a pregnancy-related illness and other workers suffering from any illness unrelated to pregnancy come within the scope of Article 141 EC etc relating to equal pay for men and women.
The Court found the rule of a sick leave scheme that provides a reduction in pay for female workers absent prior to maternity leave due to pregnancy-related illness and male workers absent through any other illness is not discriminatory if it applies to both equally.
I've checked this situaiton also with the Employment Rights Unit at the Dept. Enterprise, Trade and Employment. No employer in Ireland is legally obliged to pay staff while on sick leave and there is no legislation dealing with sick leave.
If you were on pregnancy-related sick leave from work and your contract of employment (and custom and practice in the workplace) does not provide for pay while off sick, then you have been over-paid and you are required to repay the overpayment. Deductions from salary by the employer are governed by [broken link removed]. Similarly, if any other employee was off work sick and there is no provision for paid sick leave, then they would be required to re-pay back this money too.
However, if your contract of employment specifically provides that a portion of sick leave is paid by the employer, you may have grounds for objecting to being obliged to repay the full amount.
The Court ruling in the McKenna case is available by searching the ECJ website here: [broken link removed]
Without further information as to what exactly is the policy in your workplace, it is impossible to give you a definitive response as to whether or not your employer is correct to demand such a repayment. The Employment Rights Unit are contactable at 1890 201 615.
I hope the above has been of assistance, however.