Introduction
The legal maxim "he who asserts must prove" encapsulates the fundamental principle of the burden of proof in legal proceedings. In the context of UK labour law, this means that the party making a claim or an assertion in an Employment Tribunal is typically responsible for providing evidence to support it. This principle ensures that allegations are not upheld without a sufficient factual basis. However, while this rule forms the general starting point, the complex nature of the employment relationship and the potential for an imbalance of power between employer and employee have led to important statutory modifications. This essay will explain the general application of the burden of proof in labour law before examining the specific and significant ways in which it is modified in claims of unfair dismissal and discrimination.
The General Burden of Proof
In most civil litigation, including many employment claims, the legal burden rests on the claimant to prove their case on the balance of probabilities. This means the tribunal must be satisfied that it is more likely than not that the events occurred as the claimant alleges. For example, in a claim for unauthorised deductions from wages under the Employment Rights Act 1996, the employee (the claimant) must first assert and provide evidence that a deduction was made from their wages. They must establish the facts that form the basis of their claim. If the employee cannot produce a prima facie case—that is, evidence which, if not rebutted, would be sufficient to prove their claim—the claim will fail without the employer needing to present a defence. This straightforward application of the principle ensures that the tribunal's process is grounded in evidence presented by the party seeking a remedy.
The Shifting Burden in Unfair Dismissal
The principle is significantly adapted in the context of unfair dismissal claims. While an employee must still assert and prove certain foundational facts—namely that they were an employee who was dismissed and have the necessary qualifying service—the burden of proof then shifts. Section 98(1) of the Employment Rights Act 1996 (ERA 1996) expressly places the burden on the employer to show the reason for the dismissal. The employer must prove that the reason falls within one of the potentially fair reasons set out in section 98(2) of the ERA 1996, such as conduct, capability, or redundancy. If the employer fails to provide a reason or provides one that is not potentially fair, the dismissal will be found to be unfair.
If the employer successfully shows a potentially fair reason, the burden of proof becomes neutral. The tribunal must then decide, under section 98(4) of the ERA 1996, whether the dismissal was fair or unfair in all the circumstances. At this stage, it is not for one party to prove the other was wrong; rather, the tribunal assesses the employer's actions against the standard of a reasonable employer. This statutory modification recognises that the employer holds the knowledge and information regarding why the dismissal occurred, and it is therefore fair and logical to require them to justify their actions.
The Reverse Burden in Discrimination Claims
An even more pronounced shift in the burden of proof occurs in discrimination claims, governed by section 136 of the Equality Act 2010. This provision establishes a two-stage process designed to address the difficulty claimants often face in proving discrimination, as the relevant evidence is often held exclusively by the employer.
First, the claimant must prove facts from which the tribunal could conclude, in the absence of any other explanation, that a contravention of the Act has occurred. If the claimant successfully establishes this prima facie case, the burden of proof reverses and shifts to the employer. The employer must then prove that their actions were in no sense whatsoever on the prohibited grounds (e.g., race, sex, disability). If the employer cannot provide a non-discriminatory explanation for the treatment, the tribunal must uphold the complaint. The guidance provided in Igen Ltd v Wong [2005] EWCA Civ 142 remains influential in how tribunals approach this shifting burden, highlighting that it is a crucial mechanism for enabling claimants to challenge potentially discriminatory conduct effectively. This reversal acknowledges the inherent evidentiary challenges in discrimination cases and ensures that employers are held to account for their decisions.
Conclusion
In conclusion, the principle "he who asserts must prove" serves as the default rule in UK labour law, placing the initial responsibility on the claimant to establish their case. However, this general rule is not absolute. In the key areas of unfair dismissal and discrimination, Parliament has intervened to modify the burden of proof. By shifting the burden to the employer to show the reason for a dismissal or to disprove an allegation of discrimination once a prima facie case has been made, the law recognises the informational and power imbalances inherent in the employment relationship. These statutory adaptations are not a rejection of the basic principle but a necessary and pragmatic adjustment to ensure fairness and justice in the specific context of employment disputes.
References
- Igen Ltd v Wong [2005] EWCA Civ 142
- Equality Act 2010
- Employment Rights Act 1996


