Can your employer fire you without a warning for something they let you do in the past?
The two key issues to consider if you've been fired without a warning in any employment context or dispute are:
1) Is there an employment contract (including union agreement) which has terms covering or relating to discipline and termination? If so, its terms or provisions will govern and must be honored by both parties.
2) Is there illegal discrimination going on—e.g. is one employee being treated worse because of his or her race, sex, religion, age over 40, or disability? (Though note: only certain specific forms of “discrimination” are actually illegal. For example, in many states, it is permissible to fire someone because of sexual orientation.)
If there is no contract, then an employee is an “employee at will.” As the term implies, an employee at will works at the will—or whim, if you prefer—of the employer. An employer may fire an employee at will at any time, for any reason, without notice.
Since employment at will is literally at will, an employer may fire someone for behavior that the person was previously allowed to do; it is completely at the employer’s discretion. Indeed, and not to put too fine a point on it, an employer could fire someone because that person disagreed over who should have been eliminated from last week’s American Idol. Therefore, the previous allowing, or at least ignoring of, certain actions or behavior does not obligate the employer to allow it in the future.
However, as per 2), above, if employee A is fired for doing things that employees B through G do, and the only difference is employee A’s race, sex, religion, etc., then there may be a discrimination claim against the employer. Although in theory an employer of an at will employee may fire an employee for any reason or for no reason at all, many employers avoid firing employees without company policies that require that employees be warned before firing. This is because a smart employer tries to avoid the appearance of discrimination or sexual harassment wtih proper practices. An employee who feels they may have been discriminated against or sexually harassed or fired for some other unlawful reason should consult with an employment attorney.