The Most Important Evidence in Your Employment Case
Employment cases are won or lost on evidence — not on feelings, not on outrage, not on the certainty that something wrong was done. The evidence is what transforms a suspicion into a proof. Across every type of employment case, certain categories of evidence appear again and again as the evidence that matters most.
An employee who has been wrongfully terminated knows what happened. They felt the shift in their supervisor’s attitude. They saw the pretextual PIP. They know the stated reason is false. But knowing is not proving. The gap between the two is filled by evidence — and the evidence that fills it most effectively falls into a small number of categories that are consistent across discrimination cases, retaliation cases, harassment cases, and wrongful termination cases.
Understanding what evidence matters — and why — helps the employee preserve it when it is available and recognize its significance when it appears.
The timeline
In every employment case, the timeline is the foundation. When did the protected event occur — the complaint, the leave request, the disability disclosure, the whistleblower report? When did the adverse action follow? How close together were they?
Temporal proximity — the closeness in time between the protected event and the adverse action — is the single most common form of circumstantial evidence in employment cases. An employee who is fired two weeks after filing a harassment complaint has stronger circumstantial evidence of retaliation than one who is fired two years later. The shorter the interval, the stronger the inference.
The timeline does more than establish proximity. It reveals the sequence: what the employer knew, when it knew it, and what it did in response. A chronology that shows satisfactory performance before the protected event and sudden criticism after tells a story that the employer will struggle to rewrite.
How to preserve it: Write down key dates — the date of the complaint, the date of the leave request, the date the treatment changed, the date of the termination — as soon as possible. The timeline you construct from memory in the weeks after the termination is more reliable than the one you reconstruct months later.
The comparators
How were similarly situated employees treated? An employee fired for “poor performance” while a colleague with a comparable or worse record was retained has evidence that the stated reason is pretextual. An employee denied a promotion while a less qualified person of a different race, gender, or age was promoted has evidence of discrimination.
Comparator evidence works because it controls for the stated reason. If the reason is performance, but other employees with similar performance were not fired, the reason does not explain the outcome. Something else does — and when the employee is the only person of their race, or the only person over fifty, or the only person who filed a complaint, the “something else” has a name.
How to preserve it: Note the identities of employees in similar positions — same supervisor, same role, same level of performance — and how they were treated. Were they disciplined for the same conduct? Were they given the same opportunities? Were they retained when you were not? These comparisons become central to the case.
The employer’s shifting explanations
A true reason does not need to be revised. When the employer gives one explanation for the termination in the exit meeting, a different explanation in the unemployment hearing, and a third explanation in litigation, the instability of the justification is evidence that none of them is the real one.
Shifting explanations are among the most powerful forms of pretext evidence because they come from the employer itself. The employer is not being contradicted by an outside witness — it is contradicting itself. And each new version of the story raises the question: if the first reason was sufficient, why did it change?
How to preserve it: Note exactly what you were told in the termination meeting — who said it, what words they used, what reason they gave. Compare it to any subsequent communication — the termination letter, the employer’s response to your unemployment claim, any statement from the employer’s attorney. The comparison is the evidence.
The documentary record
The documents the employer created during the employment — performance reviews, written warnings, emails, internal memos — are the employer’s own assessment of the employee, created before the termination, for purposes unrelated to litigation. They are among the most credible forms of evidence because they were not created to prove a case — they were created in the ordinary course of business.
When the documentary record contradicts the employer’s stated reason, the contradiction is devastating. An employer that fires an employee for “poor performance” must contend with a file full of positive reviews, commendation emails, and the absence of any prior warning. The documents tell a story that the employer’s post-hoc characterization cannot override.
How to preserve it: Request your personnel file under Labor Code section 1198.5. Save copies of performance reviews, written commendations, relevant emails, and any other documents you received during the employment. The documents you preserve before the termination may not be available after — the employer controls the file, and documents can be lost, altered, or destroyed.
The pattern
A single incident of discrimination is hard to prove. A pattern — the same supervisor discriminating against multiple employees of the same protected class, the same employer retaliating against multiple whistleblowers, the same pretextual justification applied to multiple terminated employees — is far more persuasive.
Pattern evidence transforms an individual claim into a systemic one. It shifts the jury’s question from “did this one thing happen?” to “how many times did it happen before someone was held accountable?” The answer almost always favors the plaintiff.
How to preserve it: Talk to former colleagues — carefully, and with your attorney’s guidance. Learn whether others experienced similar treatment. Identify anyone who left under similar circumstances. The discovery process will eventually reveal the employer’s records, but the employee’s own knowledge of the pattern is where the investigation begins.
The absence of documentation
Sometimes the most important evidence is what does not exist. An employer that claims the termination was for performance but has no written warnings, no documented counseling sessions, no performance improvement plan, and no contemporaneous record of the problems it now claims were serious has a credibility problem.
The absence of documentation is evidence of pretext because a genuine performance problem generates documentation. Supervisors write memos. HR creates records. Warning letters are issued. When the file is clean — when years of employment produced no negative documentation until the termination itself — the inference is that the performance problem was manufactured to justify a decision that had already been made.
How to identify it: When you receive your personnel file, review it not only for what is present but for what is absent. If the employer’s stated reason is performance, and the file contains no evidence of performance problems, the absence is your evidence.
The direct evidence
Direct evidence of discriminatory intent — a supervisor’s statement, an email expressing bias, a text message revealing the real reason — is the rarest and most powerful form of evidence. A supervisor who says “we need younger people in this department” before firing the oldest employee has provided direct evidence of age discrimination. An email that says “she’s been a problem since she got pregnant” is direct evidence of pregnancy discrimination.
Direct evidence is rare because most employers are careful about what they put in writing and what they say in front of witnesses. But it exists more often than employers realize — in unguarded moments, in casual emails, in text messages between supervisors who assumed no one else would see them. Discovery is designed to find these communications, and when they are found, they are often case-determinative.
How to preserve it: If you heard a discriminatory statement, write down exactly what was said, by whom, when, and who else was present — immediately, before the memory fades. If you received an email or text message that reveals discriminatory intent, save it to a personal device. Direct evidence is the hardest to find and the easiest to lose. Preserve it the moment you recognize it.
The evidence that wins employment cases is not exotic. It is the timeline, the comparators, the shifting explanations, the documentary record, the pattern, the absence of documentation, and the rare direct statement. Each of these categories is available to the employee who knows what to look for and who preserves it when it matters most — which is now, not later.
This article is general information about California law and is not legal advice. Every situation turns on its particular facts.