Understanding which of the two your case actually rests on is the single most useful thing you can do before you refer, because the two are argued differently and they can lead to very different outcomes.
This guide explains the law generally and is not advice about your own case.
Substantive fairness: was there a good reason?
Substantive fairness is about the why. Did the employer have a fair reason to dismiss you, and was dismissal an appropriate response to it?
The recognised categories of fair reason are, broadly, misconduct, incapacity including poor performance and ill health, and the employer's operational requirements, which is retrenchment.
Two things sit inside this test that people often miss.
The employer has to prove the reason. It is not enough to believe you did something. In a misconduct case the employer generally carries the burden of showing, on a balance of probabilities, that you did it.
Dismissal has to be an appropriate sanction. Even where the conduct is proved, dismissal may be too severe for it, depending on factors like the seriousness of the conduct, your record, your length of service, and whether the employment relationship can still work. A first offence that caused no real harm, from someone with ten clean years, is a different case from a repeated deliberate one.
Procedural fairness: was the process fair?
Procedural fairness is about the how. Broadly, whether the employer investigated, told you what you were accused of, gave you a real chance to respond, allowed assistance, decided through someone who had not made up their mind, and told you the outcome.
Detail: Dismissed without a hearing: is that unfair?
Why the difference matters to you
Here is the practical part, and it is the part most guides skip.
Winning on substance and procedure together is the strongest position. The employer had no good reason and went about it badly.
Winning on substance alone is strong. There was no fair reason to dismiss you. Whether the paperwork was tidy matters less if the underlying reason does not hold.
Winning on procedure alone is real but narrower. The reason may have been sound, and the failure is in how the employer got there. That can still make the dismissal unfair.
It is worth going in with a realistic picture of what a case is worth rather than a hopeful one. That is what stops people spending eight months on an outcome that was never likely.
Working out which one you have
Ask yourself two plain questions and answer them separately.
On the reason. Did you do the thing you were accused of? If yes, was dismissal a proportionate response, given your record and the seriousness? If the employer's reason was performance or retrenchment rather than misconduct, was it real, and was it applied properly?
On the process. Were you told the allegation clearly? Were you given time to prepare? Did you get to respond before the decision, not after? Were you allowed help? Was the person deciding already involved in the incident? Were you told why?
Most people answer the first set emotionally and the second set factually. Try to do both factually. The second set is easier to evidence, which is one reason procedural failures come up so often.
A note on honesty
If you did the thing, and it was serious, and the employer ran a proper process, you may not have a case worth referring. That sentence is uncomfortable and most of the market will not say it to you, because most of the market earns when you proceed.
We do not. FairCase gives you a probability score out of 100 with the calculation shown, and when the honest answer is that your case is weak, the report says so. Finding that out in five minutes costs you nothing. Finding it out in eight months costs you a great deal.