(1) The reality is that you can be fired at any time regardless of your disability, disability leave or any other circumstances. No one can force the employer to continue employing you if they don’t want to, except in limited circumstances (i.e. employment relationship covered by a labor union agreement, employment with a public agency and a few other limited circumstances). Otherwise, if you are an at-will employee at a private company, you can leave at any time and you can be terminated at any time.
(2) The more correct question is whether firing you while on disability leave or medical leave would be illegal and could be a basis for a disability discrimination and wrongful termination case. The answer to this question depends on the specific circumstances of your employment and your termination. However, the most important factor is whether the employer had a legitimate reason for terminating you, or there is sufficient evidence that the reason given is just an excuse or a pretext for terminating you because of your disability and disability leave.
Here is two common termination patterns to illustrate this:
(a) Your employer cuts 20% of its workforce. Your position along with other is being eliminated. Some of the employees who are laid off are on disability leave while others are not. The employer appears to have a legitimate business reason for your separation, and unless there is specific evidence that the reason for your termination is your disability, there is no basis to file any kind of case.
Compare this to (b) a situation where shortly after you return from disability leave, your employer issues a negative performance review to you despite your long history of good work performance with the same company, or falsely accuses you of something, or tries to discipline you for a minor infraction that took months ago, and/or shows that he is unhappy about you taking time off or doesn’t even believe that you have a real medical condition. Shortly after, you are being terminated for poor performance or “not being a team player” or some other vague, subjective reason. This type of situation might be well worth investigating and there is likely a legitimate wrongful termination case that can be brought.
Of course, pattern (b) this is exactly where an experienced attorney should help you evaluate the whole picture and determine whether there is sufficient evidence to prove a case. These types of cases are rarely black and white. The employer will always have some arguments and defenses for their actions. Therefore, taking the extra time to evaluate the case thoroughly before filing it to make sure there is a strong case is a very good idea.