This article applies to England and Wales.
Evidence in whistleblowing judgments
In brief: Whistleblowing judgments are the most witness-heavy in the population: in substantial judgments from England and Wales, 2023–25, witness statements are mentioned in 75% against 67% overall. Employer paperwork sits at population rates, WhatsApp rose from 7% to 19%, disciplinary policies fell from 11% to 4% and incident reports from 6% to 2%.
Last updated: September 2026
By Yerty | Analysis of published Employment Tribunal decisions, 2017 to 2025. Part of the evidence by claim type series.
A whistleblowing claim is about a disclosure, the employer's reaction to it, and the link between the two. The evidence profile shows what that means in practice: more witness evidence than any other claim type, and paperwork that looks like an unfair dismissal file with the disciplinary policy taken out.
This piece takes the public interest disclosure column of Yerty's evidence by claim type analysis and reads it on its own: 152 judgments in 2017–19 and 161 in 2023–25. One row that appears in the underlying data, the word "disclosure", is left out of this piece deliberately: in whistleblowing judgments it is the statutory phrase "protected disclosure", not document disclosure, and it appears in 76% of them for that reason.
Summary
- Witness statements at 75%, the highest rate of any claim type, up from 64%.
- Employer paperwork at population rates: contract of employment 44%, dismissal letter 14%, investigation report 11%, written warning 9%.
- The disciplinary policy fell from 11% to 4% and written warnings from 16% to 9%.
- WhatsApp rose from 7% to 19%; Microsoft Teams reached 4%, the highest rate of any claim type; social media 1% to 7%.
- Incident reports fell from 6% to 2% and photographs from 11% to 6%.
Evidence in whistleblowing judgments
Share of judgments that mention each type of evidence at least once. The final column is every judgment in the population, for comparison. 152 judgments in 2017–19 and 161 in 2023–25.
Evidence mentioned in whistleblowing judgments (the word 'disclosure' is excluded: in these cases it is the statutory phrase) · share of judgments, ■ 2017–19 (n 152) → ■ 2023–25 (n 161) · ○ all cases 2023–25
Sorted by change. Rows under 3% in both periods are omitted; the full figures are in the table below. A mention is not reliance.
| Evidence | Whistleblowing 2017–19 | Whistleblowing 2023–25 | All cases 2023–25 |
|---|---|---|---|
| Witness evidence | |||
| Witness statement | 64% | 75% | 67% |
| Employer documents | |||
| Contract of employment | 39% | 44% | 50% |
| Written warning | 16% | 9% | 13% |
| Final written warning | 10% | 5% | 10% |
| Dismissal letter | 9% | 14% | 11% |
| Job description | 10% | 9% | 11% |
| Disciplinary policy | 11% | 4% | 11% |
| Investigation report | 9% | 11% | 10% |
| Resignation letter | 6% | 7% | 7% |
| Appeal letter | 2% | 6% | 6% |
| Employee handbook | 2% | 3% | 4% |
| Grievance letter | 3% | 2% | 4% |
| Personnel file | 3% | 1% | 2% |
| Pay and time paperwork | |||
| Payslips | 5% | 5% | 11% |
| Rota | 11% | 13% | 10% |
| P45 | 4% | 5% | 5% |
| Timesheets | 6% | 6% | 5% |
| Bank statements | 1% | 3% | 3% |
| Medical evidence | |||
| Occupational health | 14% | 16% | 17% |
| Fit note | 1% | 7% | 9% |
| Medical records | 3% | 6% | 4% |
| Impact statement | 3% | 2% | 4% |
| Medical report | 3% | 2% | 2% |
| Notes made at the time | |||
| Diary | 9% | 5% | 5% |
| Minutes of the meeting | 3% | 5% | 4% |
| Contemporaneous notes | 1% | 2% | 2% |
| Incident report | 6% | 2% | 2% |
| File note | 1% | 2% | 1% |
| Messages and images | |||
| 7% | 19% | 16% | |
| Text messages | 7% | 5% | 7% |
| Social media | 1% | 7% | 5% |
| Photographs | 11% | 6% | 5% |
| Screenshots | 1% | 4% | 3% |
| Microsoft Teams | 0% | 4% | 2% |
| Voicemail | 1% | 1% | 2% |
| Phone records | 0% | 2% | 1% |
n: Whistleblowing 152 / 161; all cases 2,029 / 1,738. A judgment is counted under every claim type among its claims.
Witness evidence
A claim under Part IVA of the Employment Rights Act 1996 turns on what the worker disclosed, whether they reasonably believed it was in the public interest and tended to show one of the listed matters, and whether the detriment or dismissal was because of it. Much of that is evidence of belief and of motive, and the table shows the consequence: witness statements are mentioned in 75% of whistleblowing judgments, eight points above the population and the highest rate of any claim type. The rise from 64% is also the largest.
Employer paperwork
The employer documents sit close to the population. The contract of employment is mentioned in 44% (population 50%), the dismissal letter in 14% (up from 9%), the investigation report in 11% and the appeal letter in 6%. What fell is the disciplinary file: disciplinary policies from 11% to 4%, written warnings from 16% to 9%, final written warnings from 10% to 5%. The warnings fall is in every claim type; the disciplinary policy fall is sharper here than anywhere else, on a column of 161 judgments.
Grievance letters are at 2–3% in both periods, lower than in any discrimination column. A whistleblower's disclosure is rarely made in a document called a grievance.
Messages and contemporaneous evidence
WhatsApp rose from 7% to 19%. Microsoft Teams, at 4%, is at twice the population rate and the highest in any column, which fits claims that often arise in office and professional settings. Social media rose from 1% to 7%.
The forms of contemporaneous evidence that fell are the ones a whistleblower once relied on to show what they had reported and when: incident reports from 6% to 2% (the highest rate of any claim type in 2017–19) and photographs from 11% to 6%. Diaries fell from 9% to 5%. Contemporaneous notes are flat at 2%. Fit notes rose from 1% to 7%, which tracks the stress and sickness absence that these claims commonly involve rather than any change in the claim itself.
Method and limits
Population and matching are those of the hub analysis: single-claimant merits decisions with written reasons, England and Wales, one judgment per case, 20,000 to 60,000 characters. Each figure is the share of judgments containing the exact phrase at least once. A judgment is counted under a claim type if that claim type is among its claims, so a judgment can appear in several claim-type columns and the columns do not sum to the population. A mention is not reliance: a judgment that rejected a document or noted its absence counts the same as one that accepted it. No category totals are given.
Frequently asked questions
What evidence appears most often in whistleblowing judgments?
In substantial judgments from 2023–25: witness statements (75%), the contract of employment (44%), WhatsApp (19%), occupational health (16%), dismissal letters (14%), rotas (13%) and investigation reports (11%). Figures are England and Wales, single-claimant, one judgment per case, and count judgments that mention the evidence at least once.
Why are witness statements so common in whistleblowing cases?
Because the claim turns on what was disclosed, what the worker believed and why the employer acted. Witness statements are mentioned in 75% of substantial whistleblowing judgments in 2023–25, the highest of any claim type, up from 64% in 2017–19.
Is the word "disclosure" counted as document disclosure?
No, and it is left out of this piece for that reason. In whistleblowing judgments "disclosure" is the statutory phrase "protected disclosure": it appears in 76% of them, against 17–35% in other claim types. Counting it as a document type would be wrong.
How often is WhatsApp mentioned in whistleblowing cases?
In 19% of substantial whistleblowing judgments from 2023–25, up from 7% in 2017–19. Microsoft Teams reaches 4%, the highest rate of any claim type, and social media 7%, up from 1%. Text messages fell slightly, from 7% to 5%.
Have incident reports become less common?
Yes. Incident reports are mentioned in 2% of substantial whistleblowing judgments in 2023–25, down from 6%, which was the highest rate of any claim type. Photographs fell from 11% to 6% and diaries from 9% to 5% over the same period.
Does a document being mentioned mean the tribunal relied on it?
No. The counts include judgments that rejected a document, gave it little weight or noted that it was missing. The figures describe what judgments discuss, not what decided the case. Whistleblowing claims in particular can turn on oral evidence of what was said and believed.
Analyse the data
Witness statements appear in three whistleblowing judgments in four. Query evidence terms in whistleblowing judgments by year and sector.
Intelligence Hub →Manage your evidence
A whistleblowing claim starts with the disclosure itself. Keep it in its original form, with who received it and when.
Case Hub →Sources
Analysis of published Employment Tribunal decisions, 2017 to 2025, drawn from the public register on GOV.UK under the Open Government Licence v3.0. Population as stated in the hub analysis; 152 judgments with a whistleblowing claim in 2017–19 and 161 in 2023–25.
Related reading: what evidence do I need for a whistleblowing claim, what evidence tribunal judgments describe, 2017 to 2025, and tribunal evidence is moving from paper to screen.
Other pieces in this series: unfair dismissal, disability discrimination, wages and working time, race, sex and age discrimination, redundancy.