Workplace Investigations: What HR Professionals Need to Know

A complaint lands on your desk. Whether it is an employee alleging harassment or an FLSA violation, you are legally required to investigate these complaints. Your investigation must be prompt, impartial, and thoroughly documented to withstand any EEOC or federal scrutiny if the case comes to trial.

In fiscal year 2024, the volume of discrimination, harassment, and retaliation cases reached 14.7 per 1,000 employees. This was a record-high benchmark in discrimination cases. The EEOC received 88,531 new discrimination charges, and prevailed in 97% of cases it resolved. Almost half of all cases involved charges of retaliatory behavior.

For HR professionals, the workplace investigation is not a procedural formality. It is one of the primary legal defenses available to employers facing harassment and discrimination claims, and one of the most common places where that defense fails. This guide explains the legal framework governing workplace investigations, what the EEOC and courts require, the key steps of a defensible process, and where HR professionals most often go wrong.

The Legal Framework: Why Investigations Are a Legal Obligation

Title VII and the Faragher-Ellerth Defense

The cornerstone of the obligation to investigate stems from two landmark U.S. Supreme Court cases. Faragher v. City of Boca Raton and Burlington Industries, Inc. v. Ellerth established what employment lawyers call the Faragher-Ellerth affirmative defense. An affirmative defense is one in which the defendant acknowledges that the harassment occurred but that it did not result in an adverse employment action.

Under the Faragher-Ellerth defense, an employer can limit or avoid liability by proving two things: first, that the employer exercised reasonable care to prevent and promptly correct harassing behavior; and second, that the employee unreasonably failed to take advantage of the employer's complaint procedures.

A well-conducted investigation is the primary mechanism by which an employer demonstrates the first prong of this defense. An inadequate or delayed investigation not only fails to help; it can also harm the employer's legal position by demonstrating that the organization did not take the complaint seriously.

The EEOC's 2024 Enforcement Guidance on Harassment

In April 2024, the EEOC issued its Enforcement Guidance on Harassment in the Workplace, the agency's first comprehensive update on harassment standards in more than 25 years. The guidance makes clear that employers have a legal obligation to conduct a "prompt and adequate investigation" once they have notice of potentially harassing conduct, and to take "reasonable corrective action" to prevent recurrence.

The guidance provided an example of an inadequate investigation. In the example, the investigator was a friend of the accused supervisor. They were unfamiliar with federal anti-discrimination laws and had no investigation experience. They conducted brief interviews. Finally, they issued a one-page memorandum and concluded without explanation that there was no basis for the complaint. The EEOC found that the investigation failed the adequacy standard. The lesson for HR professionals is that the investigation process must reflect a genuine, impartial effort to determine the facts, not a process designed to reach a predetermined conclusion.

Additional Statutes That Create Investigation Obligations

Title VII is the most commonly cited basis for investigation obligations, but it is not the only one:

• The ADA prohibits disability-based harassment and requires the same duty to investigate as Title VII when an employee complains of harassment based on a disability.
• The ADEA imposes investigation obligations when employees aged 40 or older complain of age-based harassment or discrimination.
• The NLRA limits how investigations can be conducted when they involve protected concerted activity, such as employees discussing wages, working conditions, or organizing. Employers must be careful not to broadly prohibit employees from discussing matters related to investigations in ways that chill NLRA rights.
• The PWFA, which took full effect in 2023, created new investigation obligations when employees report discrimination or failure to accommodate related to pregnancy, childbirth, or related conditions.
• State and local laws in many jurisdictions impose additional requirements. California, New York, and Illinois have anti-harassment training that specifies what complaint procedures and investigation processes must include.

What Makes a Workplace Investigation Legally Defensible

Courts, the EEOC, and employment law practitioners identify five core characteristics of a legally defensible investigation. Failing on any of these dimensions can undermine the investigation's conclusions and the employer's legal position.

#	Characteristic	What It Requires
1	Prompt	The investigation must begin reasonably soon after the employer receives notice of the complaint. The EEOC's 2024 Harassment Guidance notes that opening an investigation one day after a complaint was made is prompt; waiting two weeks without explanation in the face of allegations of physical touching likely is not. The key standard is "reasonably soon" given the nature and severity of the allegation.
2	Impartial	The investigator must not have a direct reporting relationship to either party, a personal friendship or conflict with either party, or a predetermined view of the outcome. The EEOC's guidance explicitly noted that an investigator who was a friend of the accused supervisor failed the impartiality standard. Consider whether an external investigator or employment counsel is appropriate for senior-level or high-risk allegations.
3	Thorough	The investigation must gather all relevant evidence: interviewing the complainant, the accused, and all material witnesses; reviewing documentary evidence (emails, text messages, performance records, schedules, surveillance footage if applicable); and following up on leads that emerge during the process. A one-page memorandum, based on a few brief interviews, does not meet the standard of thoroughness.
4	Confidential	Investigators must maintain confidentiality to the extent possible, sharing information only with those who need it to conduct the investigation or implement corrective action. At the same time, blanket confidentiality instructions that prohibit employees from discussing the matter with anyone can violate NLRA Section 7 rights. Confidentiality instructions should be tailored to the legitimate business interest at stake.
5	Documented	Every step of the investigation must be documented: the complaint received, the investigation plan, interview notes, documents reviewed, findings, and corrective action taken. Documentation creates a contemporaneous record that demonstrates what the employer knew, when it knew it, and what it did about it. In litigation, the documentation is often the investigation.

The Eight Steps of a Workplace Investigation

Step 1: Receive the Complaint and Assess

When a complaint is received, regardless of the source, the first step is to assess whether and what type of investigation is warranted. Not every complaint requires a formal investigation. Any allegation of harassment, discrimination, retaliation, or policy violation that could violate a federal statute should be investigated. Consult employment counsel early, particularly when the allegation involves a senior leader, a systemic issue, or potential criminal conduct.

Step 2: Take Interim Protective Measures if Needed

If the nature of the allegation poses an ongoing risk to the complainant or others, such as physical harassment or threats, consider interim measures. Temporary schedule adjustments, remote work assignments, or a directive that the parties not interact should be considered. These measures should be framed as protective rather than punitive and should not disadvantage the complainant. Do not place the complainant on leave while the accused remains at work unless there are specific operational reasons to do so.

Step 3: Designate an Appropriate Investigator

The investigator should be neutral, trained in investigation techniques, and familiar with the relevant legal standards. They should not have a supervisory relationship with either party or a personal connection that could compromise their impartiality. For high-stakes allegations, such as those involving senior leadership, potential systemic discrimination, or conduct that could result in significant liability, you should consider engaging outside employment counsel to conduct the investigation. An external investigator provides impartiality, expertise, and, in some circumstances, protection of the attorney-client privilege for the investigation report.

Step 4: Plan the Investigation

Before conducting interviews, develop a written investigation plan. Your plan should:

• Identify the allegations
• Witnesses to be interviewed, and in what order
• Documents to be reviewed, including online documentation
• Legal standards applicable to conduct

Typically, you will want to interview the complainant first, then the accused(s), then any third-party witnesses. This plan provides structure, ensures the investigation is comprehensive, and, in retrospect, demonstrates that the employer approached the matter systematically.

Step 5: Conduct Witness Interviews

Begin each interview by explaining the purpose of the investigation, the confidentiality expectations (appropriately tailored to comply with NLRA requirements), and that retaliation against anyone for participating is prohibited. Use open-ended questions that encourage detailed responses. Avoid leading questions or yes/no questions that seem to channel witnesses toward a predetermined narrative. Take detailed notes during the interview or, where legally permissible and appropriate, record interviews with consent. Your state or jurisdiction may require written consent, so check with your legal department. Document not just what witnesses said but their demeanor, any inconsistencies, and follow-up questions that arose.

Practical Note: NLRA Limits on Confidentiality Instructions. When instructing witnesses to keep investigation matters confidential, instructions must be justified by a specific, legitimate business interest (such as preventing destruction of evidence or witness intimidation) rather than applied as a blanket rule. Overly broad confidentiality instructions can constitute unfair labor practices under the NLRA. Consult employment counsel when drafting confidentiality guidance for witnesses.

Step 6: Gather and Review Documentary Evidence

Documentary evidence often shapes investigation conclusions as much as witness testimony does. Collect and preserve relevant emails, text messages, Slack or Teams messages, performance records, schedules, access logs, surveillance footage, and any other records relevant to the alleged conduct. Place a litigation hold on any electronic data that may be relevant. Review documents before witness interviews where possible, so interviewers can ask targeted questions about specific communications.

Step 7: Evaluate the Evidence and Reach Findings

Once all evidence has been gathered, evaluate it under the applicable legal standard. Most workplace investigations apply a "preponderance of the evidence" standard. This means it is "more likely than not" that the alleged conduct occurred. Document the basis for credibility determinations when witness accounts conflict. The investigation report should clearly state the allegations, the evidence gathered, the credibility assessments made, the legal standards applied, and the factual findings.

Avoid the temptation to reach conclusions that minimize institutional inconvenience. An investigation finding that no misconduct occurred, when the evidence shows otherwise, exposes the organization to far greater liability than a finding that addresses the problem directly.

Step 8: Implement Corrective Action and Follow Up

If the investigation concludes that a policy or legal violation occurred, take corrective action. The action should be roughly equal to the severity of the conduct and to your findings. For instance, findings of assault should be dealt with more severely than findings of verbal harassment. Document the action taken. Communicate the outcome appropriately to the complainant, without revealing confidential information about specific actions taken against the accused. Confirm that the conduct has been addressed. Follow up with the complainant after a reasonable period to confirm no retaliation has occurred. Document this follow-up as well.

The Five Most Common Investigation Failures

Employment attorneys and the EEOC have identified patterns in investigation failures that cost employers in litigation. HR professionals should actively guard against:

• Delay: Investigations that begin weeks or months after the complaint is received, without a documented reason for the delay, undermine the promptness standard. Establish an intake process that ensures complaints are acknowledged and investigation timelines set within 24 to 48 hours of receipt.
• Lack of qualified investigators: The EEOC specifically cited lack of an experienced investigator as a reason for inadequate investigations. Assigning the investigation to whoever is available without vetting or training your investigators is a costly error. Invest in investigator training or build relationships with external employment counsel before you need them.
• Failure to interview all material witnesses: Interview everyone mentioned by both the complainant and the accused, and anyone mentioned by the witnesses. The EEOC cited a lack of thoroughness as a reason for finding the investigations inadequate.
• Poor documentation: Document everything, and keep all documents for each case in a separate file. If you cannot prove something was done, then legally it did not happen. Investigation notes, interview summaries, documents reviewed, and the basis for findings must all be preserved in a case file.
• Conflating investigation and discipline: An investigation is not disciplinary action. Deciding the investigation has not determined a need for disciplinary action wrecks your impartiality and can be an expensive lesson.

The Retaliation Risk: Protecting Complainants and Witnesses

Retaliation claims appeared in 42,301 EEOC charges filed in 2024. Courts and other agencies have increasingly expanded the definition of "retaliation" and begun scrutinizing employers and HR professionals who seem not to take these claims seriously.

Any adverse action taken against the complainant or a material witness, such as schedule changes, reduced assignments, or negative performance reviews that follow closely in time from the complaint or investigation, can be characterized as retaliatory, regardless of the stated business reason. The employer's burden is to document a legitimate, non-retaliatory reason for any such action and to ensure that reason is consistent with how similarly situated employees have been treated.

Follow-up after investigation closure is not optional. Check in with the complainant after sixty to ninety days. Document those conversations. If the complainant reports new concerns, treat them with the same rigor as the original complaint.

Related: How to Become a Compliance Officer | Health Issues and Workplace Protections

Building Investigation Competency: Training and Credentials

The skills needed to conduct a defensible workplace investigation require a specific combination of legal knowledge, procedural discipline, and interpersonal skill. Being able to follow an investigation checklist is not the same as understanding the legal standards behind it. HR professionals who are responsible for these investigations or who oversee teams that conduct them can benefit from formal legal education covering the statutes, case law, and EEOC guidance that define the legal landscape.

Graduate programs in labor and employment law for non-lawyers have emerged as one of the most direct ways to build this foundation. Programs like Cardozo School of Law's M.S.L. in Labor and Employment Law (Online) include Conducting Workplace Investigations as a core course in their curriculum. These classes teach investigative procedures and the legal framework that gives those procedures their authority and defensibility.

For HR professionals managing investigation programs at scale, a formal credential in employment law signals to employers that the person overseeing investigations has invested in substantive legal education. They will understand how to handle investigations, write a clear and coherent report, and defend their conclusions.

Related: Best Online MLS Programs for HR Professionals | Masters in Compliance

Bottom Line

A workplace investigation is a legal obligation and a powerful legal defense for employers in harassment claims. The investigation shows that the organization takes these claims seriously, acts on them promptly, and corrects problems when they are found. Employers who fail to do them properly or in a timely manner turn a manageable complaint into a costly EEOC charge, a federal lawsuit, and a record of institutional indifference.

For HR professionals, the investment in investigation knowledge is worth more than a degree. The EEOC's enforcement data indicates that investigations are increasing in frequency. Employers are under intense scrutiny. They need professionals who understand the legal framework, not just the organizational procedures, and who are best positioned to protect employees, limit liability, and lead their organizations through future investigations.

Build the legal foundation: M.S.L. in Labor and Employment Law (Online) at Cardozo School of Law