When a workplace investigation derails, the costs don't stop at wasted time and money. A failed workplace investigation mistakes can expose your Ontario organization to legal liability, wrongful dismissal claims, and damage to your employer brand. The problem: most investigations fail not because the facts are unclear, but because foundational mistakes made in the first week corrupt everything that follows.
We've reviewed dozens of failed investigations over the past five years. The pattern is consistent. Organizations often don't recognize they're in trouble until a tribunal or arbitrator rejects their findings, or an employee's lawyer sends a demand letter. By then, it's too late to course-correct.
The good news is that workplace investigation mistakes are almost entirely preventable. If you can identify these five warning signs early, you can pivot before your investigation becomes indefensible.
Sign 1: Your Investigator Has a Pre-Existing Relationship With One of the Parties
This is the most common fatal flaw. An HR manager who mentors the respondent, a senior leader who reports to the complainant, a colleague who socializes with either party—these relationships don't disqualify someone from conducting an investigation, but they do create a credibility problem that arbitrators and the Ministry of Labour (MOL) take seriously.
We recently worked with a client who had assigned their internal HR director to investigate a harassment complaint against a department manager. The investigator and the manager had worked together for eight years. They attended the same industry events. When the investigation concluded with a finding of "insufficient evidence," the complainant's lawyer immediately flagged the bias problem. The Ontario Human Rights Tribunal later found that the investigator's pre-existing relationship created a reasonable apprehension of bias, which weakened the weight given to their findings.
The consequence wasn't just a weakened report. It signaled to an adjudicator that the organization wasn't serious about impartiality. And once that signal is sent, you're fighting credibility battles for the rest of the case.
How to prevent it: The first step in any investigation is a conflict-of-interest check. Before you assign an investigator, ask: Do they have a reporting relationship to either party? Have they socialized with or mentored either party? Do they have a stake in the outcome? If the answer to any of these is yes, recuse them. If your organization is small and every HR person has some connection, that's the moment to bring in a third-party investigator. It costs less than litigation.
Sign 2: You're Rushing to Close Within Days
Speed kills investigations. When you're trying to wrap up a workplace investigation in three to five days, you're signaling to everyone involved—and later, to a tribunal—that you're checking a box, not finding facts.
Proper investigations take time. A straightforward single-allegation case with two or three witnesses typically takes 2-3 weeks. A more complex case with multiple allegations, systemic concerns, or a power imbalance can easily take 4-6 weeks or longer. That's because real investigation requires careful witness scheduling, thorough document collection, follow-up interviews based on emerging information, and time for the investigator to think between interviews rather than moving on muscle memory.
We worked with an Ontario manufacturer that concluded an investigation into alleged discrimination in two weeks. The investigation was thin: three witness interviews, minimal document review, and a report that read like a rushed summary. When the employee filed a Human Rights Code complaint with the Ontario Human Rights Tribunal, the tribunal noted that the investigation timeline was "inconsistent with the complexity of the allegations." The organization's credibility took a hit before the substantive hearing even began.
The other risk of speed: you miss evidence. A witness who seemed evasive in the first interview often opens up more honestly in a second conversation, once they've seen how the investigator handles sensitive material. Documents that didn't seem relevant on day two become critical on day eight, once you understand the timeline better. Rushing forces you to miss these opportunities.
How to prevent it: Establish a realistic timeline at the outset. Most Ontario investigations should assume 3-4 weeks as a baseline, longer for complex cases. Communicate this timeline to all parties upfront so there's no expectation of a rushed close. If your organization is pressuring you to wrap up faster, that's a sign you need to push back or bring in a third party who can shield the investigation from timeline pressure.
Sign 3: Witnesses Are Being Interviewed Without a Structured Plan
Ad hoc interviewing—calling witnesses into the office whenever you get around to it, asking different questions to different people, taking incomplete notes—produces inconsistent evidence and undermines your findings.
A structured interview plan means you've identified all potential witnesses before you start, you've prepared a consistent set of questions for each group of witnesses, and you've documented a clear note-taking protocol. It means the order of interviews is intentional (not random), and follow-up interviews are scheduled when new information emerges.
Without structure, you end up with a situation we see regularly: the investigator interviews the complainant first, then the respondent, then three witnesses—and each conversation is shaped by different questions and different levels of detail. When the respondent's lawyer later challenges the findings, they can point to inconsistencies in the investigative process itself. The tribunal focuses on methodology, not just conclusions.
We worked with a nonprofit that interviewed witnesses in whatever order people were available. Some interviews were 45 minutes, others were 10. Some had follow-up calls, others did not. The notes from one witness were dense and detailed; notes from another were a single paragraph. When the case went to arbitration, the opposing counsel had a field day pointing out that the investigation was haphazard. The arbitrator agreed that the methodology raised questions about the reliability of the findings.
How to prevent it: Before you conduct a single interview, create a witness interview plan. List every potential witness, categorize them (direct witnesses, indirect witnesses, character references), and prepare a core set of questions that every witness in that category will be asked. Use a standardized note-taking format—either written notes or a recorded interview, but consistently applied. Schedule all interviews in a logical sequence (usually: complainant, respondent, then witnesses). Build in time for follow-up interviews if new information emerges.
Sign 4: No Document Preservation Happened at the Outset
The moment a complaint lands on your desk, documents matter. Emails, text messages, chat logs, calendar entries, performance reviews, disciplinary files, CCTV footage—all of it is evidence. And all of it is vulnerable to loss or deletion if you don't act immediately.
We've seen cases where critical emails were deleted because no preservation notice was issued. CCTV footage was overwritten because the retention cycle wasn't paused. Text messages disappeared because the respondent's phone was reset. In each case, the loss of evidence weakened the investigation's credibility, and in some cases, created an inference of destruction of evidence that worked against the organization.
Ontario courts and tribunals take document preservation seriously. If an organization fails to preserve evidence and that loss is material to the case, an adjudicator may draw a negative inference against the organization. In simpler terms: if you lose evidence, the tribunal assumes that evidence would have supported the other side.
How to prevent it: Issue a litigation hold notice the day a formal complaint is made. The notice should identify all document custodians (the complainant, the respondent, witnesses, managers with access to relevant files), and direct them to preserve all potentially relevant documents. Specifically cover emails, messages, chat logs, phone records, calendar entries, files on shared drives, and any physical documents. For CCTV or other automated systems, notify IT to pause any automatic deletion or overwrite protocols. Document that the preservation notice was issued and received. This single step, done on day one, prevents the vast majority of document loss problems.
Sign 5: The Report Reads Like a Conclusion Looking for Evidence
This is confirmation bias in written form. The investigator has decided what they believe happened, and the report is structured to support that belief. Evidence that supports the conclusion gets prominent placement and detailed analysis. Evidence that contradicts it gets minimized, dismissed, or buried in footnotes.
Confirmation bias is the #1 reason investigations get overturned by tribunals and arbitrators. Adjudicators are trained to spot it. They look for whether the investigator's findings follow the evidence, or whether the evidence is being cherry-picked to support a predetermined conclusion.
A report that reads like "The respondent is dishonest because [three examples], and the evidence that suggests otherwise doesn't matter because [dismissal]" is confirmation bias on display. A defensible report reads like "The evidence shows X and Y. The respondent offers explanation Z. Here's why the evidence supports X and Y more credibly than Z." The difference is subtle but critical.
We reviewed an investigation where the report's conclusion was that the respondent had created a hostile work environment. But when we read through the evidence section, the actual documented instances of problematic behavior were sparse and ambiguous. Most of what the investigator cited was second-hand accounts and inferences. The report read backwards—the investigator had already decided the respondent was guilty, and the evidence was being shaped to fit.
How to prevent it: Investigator training and methodology matter here. A structured investigation process requires the investigator to document all evidence (supporting and contradictory), assess credibility systematically, and write findings that show their reasoning. The report should explain not just what the investigator found, but why other interpretations of the evidence are less credible. This takes longer to write, but it's the difference between a defensible investigation and one that falls apart under scrutiny.
How 1205 Prevents These Failures
Our investigation methodology is built around these five failure points. We use independent investigators who have no pre-existing relationships with either party. We establish realistic timelines upfront and protect them from organizational pressure. We develop structured interview plans before the first witness meeting. We issue litigation hold notices on day one. And we train our investigators to write reports where findings follow evidence, not the other way around.
The result is investigations that hold up. When we close a case, the report is defensible. If it goes to a tribunal or arbitration, we're confident in our methodology.
If you're planning an investigation or reviewing one that's already underway, ask yourself: Are we seeing any of these five signs? If yes, now is the time to course-correct—not after the findings are rejected.
Ready to talk about your investigation? Contact us to discuss your situation and explore how a structured, defensible approach can protect your organization.