Is it fair to fire one person and not the other, when the other did something as bad or worse? I was given a code to our building by someone and not a school employee, so one day I used it to let our before and after school children in. I was NEVER told I couldn't use it nor was it EVER in writing that I couldn't.So, I was terminated. Before this incident, another staff member opened the locked door to a total stranger, NEVER asked who they were, what they wanted,etc, which we aren't allowed to do.She is still employed. The school principal was in an outrage.She is in the "click". She should have been terminated as well. I know this was due to "personal" feelings, because I had been called in the office before for some false accusations. I feel they were just trying to get rid of me. I had a meeting with the CEO of the company, but nothing became of it. I told him about the other employee, but she is still there and has now been placed in the school where I was. I feel this is unfair treatment and I want justice served.

Yes they may fire who they want, they do not have to be fair, is it fair, no of course not, is it legal, yes unless you have a contract or belong to a union.

They can keep someone they like and fire someone they don't like if they want,

As long as they don't fire you for some protected class of protection, in most US states they can fire you for any or even no reason