Your Internal Investigation May Be Your Best Legal Defense: Lessons from the Sixth Circuit’s Decision in Hamm v. Pullman SST, Inc.

Thorough, prompt investigative action—properly documented—remains an employer’s strongest shield against hostile work environment, discrimination, and retaliation claims and can be outcome‑determinative in litigation. A recent published decision from the United States Court of Appeals for the Sixth Circuit underscores the point.

In Hamm v. Pullman SST, Inc. (Feb. 12, 2026), the Sixth Circuit affirmed summary judgment for an employer largely because the employer’s Human Resources team launched an immediate, comprehensive, and well‑documented investigation into an employee’s allegations of sexual‑orientation harassment. After the employee lodged a formal complaint, the Human Resources manager interviewed him the next day, then conducted nine additional interviews, including both accused employees and neutral witnesses. Although none of the witnesses corroborated the allegations, the manager still implemented multiple preventive measures: issuing a written warning to an employee for inappropriate language, mandating in‑person anti‑harassment training, and requiring all employees to re-read and re‑sign the anti-discrimination policy. The manager then followed up with the complaining employee and accepted the employee’s requested transfer to another worksite.

The complaining employee nonetheless filed suit, alleging that the employer had subjected him to a hostile work environment (among other claims). As part of that hostile work environment claim, he criticized the employer for its response to his harassment allegations.

In affirming the trial court’s judgment for the employer, the Sixth Circuit described an internal investigation as the “most significant” action an employer can take when an employee raises sensitive workplace allegations, and the ruling serves as a blueprint for employers navigating those allegations. The employer’s rapid and structured investigative response—combined with clear documentation, follow‑up communications, and additional efforts to maintain a discrimination-free workplace—proved decisive in the ensuing litigation. The Sixth Circuit’s decision reinforces a key takeaway: employers who maintain accessible reporting channels, investigate promptly and thoroughly, and document each step are far better positioned to defeat employment-related claims in court.

Key Takeaways for Employers

The Sixth Circuit’s decision in Hamm is a compelling reminder that the steps an employer takes in the hours and days following a workplace complaint can define the outcome of litigation years later.

Act Promptly. Courts may scrutinize an undue gap between a complaint and the start of an investigation, and any unexplained delay can undermine an employer’s defense. Acting promptly signals seriousness and bolsters the employer’s position in any ensuing litigation.

Investigate with Impartiality. Investigations with a true commitment to uncovering the facts, including interviews of adverse and neutral witnesses, will bolster an employer’s position. An investigation that appears superficial or outcome-driven will receive far less judicial deference.

Documentation matters. Meticulous documentation transforms a strong investigation into a winning litigation strategy. To the extent possible, each step and interview should be memorialized in writing in some fashion. Without documentation, even the most diligent investigation may be reduced to a credibility contest.

Questions? Contact a member of Miller Johnson’s Internal Investigations & Compliance team.