How to Conduct a Legally Defensible Workplace Harassment Investigation in California

A harassment complaint just landed on your desk. Maybe an employee reported unwanted comments from a coworker. Maybe someone filed a formal written complaint against a supervisor. Whatever the specifics, what you do in the next few hours and days will matter far more than most employers realize.

In California, a poorly handled workplace harassment investigation doesn't just fail to resolve the problem  it can become the problem. Under the state's Fair Employment and Housing Act (FEHA), employers who fail to investigate promptly, thoroughly, and impartially face significant legal exposure, even when the underlying conduct itself might not have created liability on its own. Getting the process right is not just good HR practice. It's the foundation of your legal defense.

This guide walks California employers through the essential steps of a legally defensible workplace investigation, so you know exactly what's required and where most investigations go wrong.

Why the Investigation Process Itself Determines Liability

Many employers assume that a harassment investigation is only relevant if the complaint turns out to be valid. That's a costly misconception.

Under FEHA, California courts evaluate not just what happened in the workplace, but how you responded to it. Landmark California cases have established that the fairness and quality of an employer's investigative process, not just the underlying allegations, can determine liability outcomes. An investigation that was biased, delayed, or sloppily documented can itself form the basis of a claim, even if the original conduct wasn't severe enough to be unlawful on its own.

On the other hand, a well-run workplace investigation signals to courts, regulators, and employees that your organization takes misconduct seriously. It also gives you the documentation you'll need if the matter escalates to litigation or a Civil Rights Department (CRD) complaint. Think of the investigation as your shield  and build it accordingly.

Step 1: Act Promptly After Receiving a Complaint

Timing matters under California law. Employers are required to initiate workplace investigations as soon as reasonably feasible after receiving notice of a potential harassment issue. Delays in starting or completing an investigation can independently create liability, regardless of what the investigation eventually finds.

For serious allegations, such as physical harassment or threats of violence, your policy should require same-day action. For less urgent complaints, contacting the complaining party within a day or two and completing the investigation within a few weeks is considered best practice. The exact timeline will depend on witness availability and the complexity of the matter, but procrastination is not an option.

One practical note: receiving a complaint doesn't always mean receiving a formal written form. If a manager observes potential harassment, or hears about it secondhand, that can be enough to trigger your duty to investigate. California law holds that managers are required to report harassment they "knew or should have known about."

Step 2: Select a Neutral, Qualified Investigator

Who conducts the investigation is just as important as how it's conducted. The investigator must be impartial; someone with no personal stake in the outcome and no relationship that could reasonably be perceived as biasing their conclusions.

Courts scrutinize investigations handled by supervisors or managers who had direct authority over the parties involved. If the complaint is against senior leadership, involves complex legal issues, or carries significant potential liability, bringing in an outside investigator is often the right call. An experienced employment law defense attorney or qualified third-party investigator can provide the neutrality and legal competence that high-stakes situations demand.

Even well-intentioned internal investigators must honestly assess whether their involvement could create a perception of bias. If there's any doubt, that perception alone can undermine an otherwise solid investigation.

Step 3: Conduct Thorough, Structured Interviews

The interview process is the core of any workplace harassment investigation. Done right, it surfaces the facts needed to reach a sound conclusion. Done poorly, it creates new problems.

California guidance from the CRD outlines several best practices for witness interviews. Parties and witnesses should be interviewed separately. The accused must be given a clear understanding of the allegations against them, though it's generally better investigative practice to share the specifics during the interview itself rather than before. All witnesses with potentially relevant information should be interviewed  including any witnesses identified by the accused party.

Use open-ended, non-leading questions throughout. Your goal is to gather facts, not to confirm a predetermined conclusion. Keep detailed written notes or summaries of each interview, and retain those records.

One important nuance: you can instruct managers to maintain confidentiality, but requiring employees to stay silent about the investigation has been held to be inappropriate in many circumstances. If you need specific confidentiality measures, consulting with the attorneys from Brereton, Mohamed, & Korte LLP, can provide those measures for you. 

Step 4: Gather and Preserve All Relevant Evidence

Witness interviews rarely tell the whole story. A thorough workplace investigation also involves collecting and preserving documentary evidence. This includes emails, text messages, Slack or Teams messages, performance records, security footage, HR complaint logs, and any other communications that touch on the alleged conduct.

The 2025 update to California's CRD Harassment Prevention Guide explicitly addresses remote and virtual workplaces, recognizing that harassment increasingly occurs through electronic means. If your team works remotely or uses digital communication platforms, those channels are fair game for evidence gathering and should be part of your standard investigation protocol.

Preserve everything as soon as a complaint is received. Deleting or failing to retain potentially relevant records  even unintentionally can create serious problems if the matter ends up in litigation.

Step 5: Apply the Correct Evidentiary Standard

One of the most common mistakes employers make during a workplace investigation is applying the wrong legal standard when reaching conclusions. Workplace investigations in California use a "preponderance of the evidence" standard, meaning the investigator determines whether it is more likely than not that the alleged conduct occurred. This is sometimes described as "fifty percent plus a feather."

Applying a higher standard such as the criminal "beyond a reasonable doubt" threshold is a recognized mistake that creates an unrealistic bar for findings. Your investigation does not need to produce certainty. It needs to produce a well-reasoned, good-faith conclusion based on the evidence gathered.

When credibility is at issue, investigators should assess factors like consistency of accounts over time, corroborating evidence, witness demeanor, and any prior complaints involving the same individuals. Document your credibility analysis in writing.

Step 6: Take Prompt Remedial Action and Document Everything

Reaching a conclusion is not the end of the process. Once findings are made, California employers must take prompt remedial action proportional to the severity of the conduct. A one-day investigation followed by a verbal reprimand for sustained racial harassment, for example, is unlikely to be considered adequate.

Corrective action should be tailored to what actually happened and should demonstrably address the risk of recurrence. Depending on the findings, that might mean additional training, a transfer, a formal written warning, suspension, or termination. Document the decision and the reasoning behind it.

After the action is taken, follow up to confirm the harassment has stopped. If a complainant asks not to pursue the matter further, that does not relieve the employer of the duty to investigate and act  particularly when allegations are serious. California law is clear that it is rarely appropriate to decline an investigation simply because a complainant asked you to drop it.

Brereton, Mohamed, & Korte LLP helps California employers structure this entire process from intake through remediation in a way that holds up under legal scrutiny.

Protecting Your Business Before a Complaint Arrives

The best time to build a defensible investigation process is before you ever receive a complaint. California law requires employers with five or more employees to have a written anti-harassment policy that covers how complaints are received, how investigations will be conducted, and what corrective actions may follow. That policy must be distributed to employees.

Beyond the written policy, supervisors must complete two hours of harassment prevention training within six months of hire or promotion, and every two years after that. Non-supervisory employees must complete one hour. Training must be interactive and documented.

If your current policies are outdated, vague, or untested, that gap will be visible if you ever face a CRD investigation or civil litigation. Working proactively with the office of Brereton, Mohamed, & Korte LLP, we can assist you in auditing and strengthening your practices now is significantly less expensive than defending against a flawed process later.

When to Involve Legal Counsel

Some investigations can be handled internally by trained HR professionals. Others cannot. If the allegations involve senior leadership, if there's a realistic chance of litigation, if the accused has already threatened legal action, or if prior complaints have been made about the same individual, involving an experienced employer defense attorney early is not optional; it's essential.

At Brereton, Mohamed, & Korte LLP, we work with employers throughout California to conduct, oversee, or review workplace harassment investigations. We understand how California courts evaluate these processes, and we help employers build records that hold up.

Frequently Asked Questions

Q: What makes a workplace harassment investigation "legally defensible" in California? 

A: A legally defensible workplace investigation is one that is initiated promptly, conducted by a neutral and qualified investigator, applies the preponderance of evidence standard, includes thorough interviews and evidence review, and results in proportional remedial action. California courts evaluate the entire process, not just the outcome, so proper documentation throughout is essential.

Q: How quickly does a California employer need to start a harassment investigation?

A: California law requires employers to begin a workplace investigation as soon as reasonably feasible after receiving a complaint. For allegations involving physical harassment or threats, same-day action may be necessary. For other complaints, contacting the complainant within a day or two and completing the investigation within a few weeks is generally considered appropriate. Delays can independently create legal liability.

Q: Can an HR manager conduct the investigation, or does it need to be an outside investigator? 

A: Either can be appropriate depending on the circumstances. Internal HR can conduct investigations when they have the training and can be genuinely impartial. However, when the complaint involves senior leadership, when internal neutrality could reasonably be questioned, or when the matter carries significant legal exposure, bringing in an external investigator or an experienced employment law defense attorney is often the safer choice.  Note: Under California law, an external workplace investigator must be either a licensed attorney or licensed private investigator.

Q: What evidentiary standard applies in a California workplace harassment investigation? 

A: California workplace investigations apply the preponderance of the evidence standard, meaning the investigator determines whether it is more likely than not that the alleged conduct occurred. Employers who mistakenly apply a higher standard, like the criminal "beyond a reasonable doubt" threshold, create an unrealistically difficult bar and risk having their findings challenged.

Q: Does the employer have to investigate even if the complainant asks them not to?

 A: Generally, yes. The 2025 CRD Harassment Prevention Guide makes clear that it is rarely appropriate to decline an investigation simply because a complainant asks the employer to let it go. If the allegations are serious, the employer must act regardless of the complainant's preference. For minor allegations, some discretion is allowed, but the employer should still follow up to confirm the issue has resolved.

Q: What happens if a California employer fails to conduct a proper workplace investigation?

 A: Failure to investigate, or conducting a flawed investigation, can form the basis of an independent FEHA claim against the employer, even if the underlying harassment was not ultimately substantiated. Courts have consistently held that inadequate investigations signal that the employer did not take reasonable steps to prevent and correct harassment, which is itself a legal violation.

Q: Are remote or virtual harassment complaints treated differently in California? 

A: No. The 2025 update to California's CRD Harassment Prevention Guide explicitly addresses remote and virtual work, confirming that harassment occurring through electronic communication channels, email, Slack, text, or video calls, is subject to the same investigation standards. Virtual investigations using video interviews are now recognized as an acceptable format when in-person meetings aren't practical.

Q: How does employer liability for harassment differ depending on who committed the harassment? 

A: Under FEHA, employers are strictly liable for harassment by supervisors. For harassment by non-supervisory employees, liability arises if the employer knew or should have known about the conduct and failed to take immediate and appropriate corrective action. In both cases, conducting a prompt and thorough workplace investigation is central to limiting or avoiding liability.

Q: Can a California employer be liable for harassment by customers or third parties?

 A: Yes. Under Government Code Section 12940(j), California employers have a duty to take reasonable steps to prevent and correct harassment by non-employees, including customers, vendors, and contractors, once they become aware that it is occurring. The standard is somewhat more flexible than for coworker harassment, but the obligation to act is real.

Q: When should a California employer involve an employment law attorney in a workplace investigation? 

A: You should involve legal counsel when the accused is in senior leadership, when there is realistic litigation exposure, when the complainant has retained an attorney, when prior complaints exist about the same individual, or when the allegations are particularly complex or sensitive. An experienced employment law attorney can help structure the investigation to meet California's legal standards and protect your organization's interests from the outset.