The employer’s genuine material factor defence

A claim for equal pay will not succeed if the employer can show that the difference in pay is genuinely due to a material factor unrelated to sex. The material factor must be:

• significant and relevant, a cause of and real reason for the difference; and

• must not itself involve either direct or indirect sex discrimination. In other words, it must not be “tainted by sex”.

For example, it can be lawful to pay workers different rates to reflect different qualifications or experience or years of service, even where over time, the original justification for the difference has disappeared because the worker who started off being less experienced or skilled has caught up (Secretary of State for Justice v Bowling [2011] UKEAT/0297/11/SM). They can also be paid differently because of their job performance, as long as it is their actual work and not their work potential that is assessed (Brunnhofer v Bank der Österreichischen Postsparkasse [2001] IRLR 571).

Different or extra tasks can justify pay differences. In Christie and others v John E Haith [2003] IRLR 670, the EAT held that a requirement for male employees to lift heavy loads could justify a pay difference. A pay difference resulting from pay protection after a TUPE transfer (see Chapter 12) can be justified under equal pay law (Skills Development Limited v Buchanan [2011] UKEATS/0042/10/BI). So can pay protection under an internal compulsory redeployment policy (Haq v the Audit Commission [2012] EWCA Civ 1621).

Other justifiable factors could include location, where one location has a higher cost of living (for example, London weighting), unsocial hours, regular night work or rotating shifts.

If the material factor accounts for some but not all of the difference in pay, the claimant is entitled to have her pay increased to reflect the part that cannot be explained by the material factor (Enderby v Frenchay Health Authority [1993] IRLR 591).

It is the employer’s responsibility to prove the existence of the genuine material factor justifying the difference in pay (Calmac Ferries Limited v Wallace [2013] UKEAT 0014/13/2210).