In your wrongful dismissal claim or law suit, you must prove that your termination was illegal.
Your employment lawyer will explain the grounds to you, but here are some ways to win:
What is Wrongful Dismissal/Wrongful Termination?
Unjust dismissal, also known as wrongful termination or wrongful discharge, occurs when an unjust termination violates any of the terms of your employment contract or a provision in Canadian employment law.
Unless they have genuine cause, Canadian employers must give employees reasonable severance pay, which is often measured in months, even years, not just weeks.
If you were fired because off your age, race, gender, national origin, religion or disability and can prove it or have evidence that you were terminated for any of these reasons, you have grounds to sue.
Whistle blowers are protected by law. You cannot be fired for exposing that your company violates a law or is commit an illegal act such as toxic spills. You will have to prove that your employers broke the law and you reported it, or that you were told to do something related to your work that violated a law and refused to do it.