And speaking of potential precipitation brings me to a cumulatively confusing shower of claims in the case of CX v Secretary of State for Justice 2025.

CX worked as a prison officer for the Secretary of State for Justice (SSJ) from November 2020 until she was dismissed in December 2021 for failing her probation.

She brought a claim in the Employment Tribunal in March 2022, acting as a litigant in person, initially raising claims including unfair dismissal, sex discrimination, religion or belief discrimination, harassment and bullying.

The claim developed considerably over the following months. The Government Legal Department asked CX to provide further particulars, and she subsequently provided a 30-page account of events.

At a preliminary hearing in December 2022, the ET identified that some of the matters in her detailed account had not been included in her original claim and that it was not always clear which allegations were intended to form part of her legal claims and which were simply background. She was therefore asked to provide further particulars in a clearer format, which she did in a further 19-page email. Following preliminary hearings, her claims were amended to include whistleblowing detriment and automatic unfair dismissal.

During disclosure, CX became aware of an Occupational Health report which referred to her emotional health and wellbeing, and history of poor mental health, indicating that she may be considered disabled. She subsequently sought to amend her claim to include disability discrimination arising from disability under section 15 of the Equality Act 2010 and a failure to make reasonable adjustments, relying on depression and anxiety.

The ET found that the proposed disability discrimination claims were not simply a relabelling of the claims CX had already brought. Instead, they would introduce new legal and factual issues, including whether CX was disabled, whether SSJ knew or ought to have known about her disability, and whether the treatment complained of arose from her disability or placed her at a disadvantage.

The ET also considered the timing of the application. Although it accepted that CX only became aware through disclosure that her mental health may amount to a disability, she had waited around four months after seeing the relevant Occupational Health information before applying to amend her claim.

The ET accepted that acting as a litigant in person could make it difficult to identify and formulate discrimination claims. However, it considered that CX had been able to provide extensive detail about the treatment she complained of and had therefore had opportunities to raise the factual basis of a disability claim earlier.

The ET considered that allowing the amendment would significantly increase the scope of the case. It was likely to require further disclosure, medical evidence, additional witnesses and more hearing time. The ET also considered the potential prejudice to CX if the amendment was refused, but concluded that she was still able to pursue her existing claims, which included several discrimination and whistleblowing complaints.

The ET therefore refused the application to amend CX’s claim.

CX therefore appealed this decision to the Employment Appeal Tribunal.

The EAT dismissed CX's appeal and upheld the ET's decision.

The EAT agreed that the proposed disability claims went beyond the allegations already contained in CX's claim. The new claims would require the ET to consider additional issues surrounding disability, the employer's knowledge of the disability, causation and reasonable adjustments. They would therefore significantly widen the factual and legal issues the ET would need to consider.

The EAT also agreed that the ET was entitled to take the four-month delay into account. The ET had not criticised CX for failing to raise disability discrimination before she knew that her mental health may amount to a disability. Instead, it had considered why she did not apply to amend her claim sooner after receiving the relevant information.

The EAT also found that the ET had properly considered the potential prejudice to both sides. Allowing the amendment would have created additional work and costs for SSJ, including further disclosure, evidence and hearing time. However, the ET had also recognised the disadvantage to CX in being unable to pursue the additional claims.

The EAT therefore concluded that the ET had been entitled to refuse the amendment.

This case highlights that an employee will not automatically be allowed to add new discrimination claims where supporting information comes to light during disclosure. Where an amendment would introduce new factual or legal issues and significantly widen the scope of the claim, the ET will consider factors including the reason for the delay, the stage of proceedings and the potential prejudice to both parties.

For employers, the case also highlights the importance of keeping clear records where performance, probation, absence and health issues overlap. Occupational Health reports, HR advice and records of discussions may become important if questions later arise about whether an employer knew, or should have known, about a potential disability. Employers should therefore ensure that performance and probation decisions are well documented and that potential health or disability issues are appropriately considered and recorded.