What is the Employer's Duty of Investigation in Dismissal Cases?

In UK employment law, employers are required to carry out a fair and reasonable investigation before deciding to dismiss an employee. This obligation forms a key part of the fairness test in unfair dismissal claims under the Employment Rights Act 1996.

An employment tribunal will often focus heavily on whether the employer investigated properly before reaching a dismissal decision. A failure to investigate adequately can render a dismissal unfair, even if there were genuine concerns about conduct or performance.

This article explains what the duty of investigation involves, how tribunals assess it, and what standards employers are expected to meet in dismissal cases in England and Wales.

Legal Basis for the Duty of Investigation

The duty of investigation is not set out in a single statutory rule. Instead, it arises from:

• Section 98 of the Employment Rights Act 1996 (fair dismissal framework)
• Case law developed through employment tribunals and appellate courts
• The “range of reasonable responses” test applied by tribunals

Under this framework, an employer must act reasonably in all circumstances, and that includes carrying out a reasonable investigation before deciding to dismiss.

What the Duty of Investigation Means

The duty of investigation requires an employer to:

• Establish the facts before making a dismissal decision
• Gather sufficient evidence to support allegations
• Consider both sides of the situation
• Avoid making assumptions or acting on incomplete information

It does not require a perfect or forensic investigation, but it must be reasonable and proportionate to the seriousness of the allegations.

When an Investigation is Required

An investigation is typically required in dismissal cases involving:

1. Misconduct allegations

Examples include:

• Theft or dishonesty
• Bullying or harassment
• Breach of workplace rules
• Gross misconduct allegations

2. Capability or performance issues

For example:

• Poor performance concerns
• Failure to meet targets
• Ill health affecting work ability

3. Other substantial reasons for dismissal

Such as:

• Breakdown in working relationships
• Loss of trust and confidence
• External regulatory restrictions

Even in redundancy situations, some level of investigation into selection criteria may still be required.

What a Reasonable Investigation Involves

Employment tribunals assess reasonableness based on context. A reasonable investigation may include:

Gathering evidence

• Reviewing documents, emails, and records
• Checking performance or disciplinary history
• Collecting physical or digital evidence where relevant

Interviewing witnesses

• Speaking to complainants
• Taking statements from colleagues
• Recording consistent accounts of events

Allowing the employee to respond

• Informing the employee of allegations
• Giving them a chance to explain
• Considering their version of events before decision-making

Appointing an impartial investigator

Where possible, the investigator should not be directly involved in the dispute or outcome decision.

Standards Expected by Employment Tribunals

Tribunals do not expect a perfect investigation, but they do assess whether it falls within a “range of reasonable responses”.

Key considerations include:

1. Proportionality

More serious allegations require more thorough investigation. For example:

• Gross misconduct allegations require detailed fact-finding
• Minor performance issues may require a lighter process

2. Fairness and impartiality

The investigation must not be biased. Tribunals will examine:

• Whether evidence was selectively used
• Whether contrary evidence was ignored
• Whether assumptions were made too early

3. Adequacy of evidence

A dismissal should not be based on:

• Rumour alone
• Incomplete information
• Unverified complaints

There must be a reasonable factual foundation.

4. Reasonable decision-making

Even if the investigation is imperfect, a dismissal may still be fair if the overall decision was reasonable in context.

Common Failures in Employer Investigations

Employment tribunals frequently find unfair dismissal where investigations are inadequate. Common failures include:

1. No investigation at all

Dismissing an employee without fact-finding is usually unfair unless exceptional justification exists.

2. Pre-determined outcomes

Where the employer has effectively decided to dismiss before investigating, the process is likely to be unfair.

3. Ignoring employee explanations

Failing to properly consider the employee's version of events can undermine fairness.

4. Inconsistent evidence gathering

Relying heavily on one side of a dispute while ignoring conflicting evidence is problematic.

5. Delay or procedural flaws

Unreasonable delays or poorly conducted interviews may affect fairness.

Role of the ACAS Code of Practice

The ACAS Code of Practice on Disciplinary and Grievance Procedures is an important reference point.

Employment tribunals take the Code into account when assessing fairness, including whether:

• A proper investigation was carried out
• The employee was informed of allegations
• A fair disciplinary hearing was held
• Decisions were based on evidence

Failure to follow the ACAS Code does not automatically make a dismissal unfair, but it can increase compensation awards if a claim succeeds.

Investigation vs Disciplinary Decision

It is important to distinguish between:

Investigation stage

• Fact-finding process
• No decision made yet
• Evidence collected and reviewed

Disciplinary stage

• Employer evaluates evidence
• Decision to dismiss or impose another sanction
• Must be based on investigation findings

A flawed investigation often undermines the fairness of the final decision.

Impact of a Poor Investigation on Tribunal Claims

If an investigation is inadequate, an employment tribunal may find:

• The dismissal was procedurally unfair
• The employer did not act reasonably
• The decision was not based on sufficient evidence

However, tribunals also consider whether a fair investigation would have made any difference to the outcome.

Burden of Proof and Investigation Quality

The employer carries the burden of showing:

• The reason for dismissal
• That a reasonable investigation was conducted
• That dismissal was a reasonable response

A weak investigation makes it harder for the employer to justify dismissal under Section 98 of the Employment Rights Act 1996.

Practical Examples

Example 1: Theft allegation without evidence

An employee is dismissed solely based on suspicion without CCTV, witnesses, or document review. This is likely unfair due to lack of investigation.

Example 2: Misconduct with partial evidence

An employer investigates an allegation, interviews witnesses, and considers the employee's explanation but reaches the wrong conclusion. This may still be fair if the process was reasonable.

Example 3: Ignoring key witness

An employer dismisses without speaking to a key witness who could support the employee. This may render the investigation unfair.

Final Thoughts

The employer's duty of investigation in dismissal cases is a central element of unfair dismissal law in England and Wales. Employers must carry out a fair, reasonable, and proportionate investigation before deciding to dismiss an employee.

While the law does not require perfection, it does require employers to gather and assess evidence properly, consider both sides, and avoid predetermined outcomes. Employment tribunals closely examine the quality of investigations when deciding whether a dismissal was fair under the Employment Rights Act 1996.

A failure to investigate adequately is one of the most common reasons dismissals are found to be unfair, particularly in misconduct and capability cases.