"Termination involuntary due to poor performance/ poor conduct. Do not rehire " - poster

Termination due to performance is easy to support via a pass fail on your ride.
The "poor conduct" is a more difficult assertion. It is highly subjective and often based on personalities or grudges. Large company HR departments would require a file a foot thick detailing every action the employee took that would lead to termination for "conduct". The cost of litigation requires it.
The "Do not rehire" is a very risky statement. A candidate terminated due to performance, who gains additional skill or experience, would be allowed a chance to reapply by most reasonable employers. For this reason, I think the "do not rehire" is coupled to the "poor conduct" statement. If there is info in your file to support their claim then take some time to reflect and learn from it. If there is an absence of supporting or correct data in your file you may have reason to bring suit. This link might may help:
CIVIL LIABILITY UNDER THE PILOT RECORDS IMPROVEMENT ACT - Legal Guides - Avvo