How binding is a signed letter of offer where all contingent requirements have been met?
Any claim you may have relating to the the offer of employment will likely be governed by contract law. The terms of the offer will generally determine your rights and obligations as well as those of the employer. You should carefully review the terms of the agreement, if you have a written agreement, to determine your rights and obligations.
Where there has been a conditional offer of employment, and that condition has not been satisfied, the contract has not been formed and the employer may withdraw. Where there has been an unconditional offer and the employee has accepted the offer there is a binding contract of employment, even if the employee has not yet begun performing on the job. If the employer wishes to withdraw the offer after it has been made and accepted it may be a breach of contract. The employer would then be liable for the consequences of that breach, for example notice pay (subject to any duty to mitigate loss on the part of the individual).
The U.S. has laws regarding being fired for discriminatory reasons, on the basis of protected classes such as age, race, gender, nationality, handicap, or religion. Wrongful discharge claims are often made on the basis of discrimination against a protected classification. If an employee isn’t protected by an employment or union contract, they are typically at-will employees who may be fired for any or no reason without notice. If a contract, such as a collective bargaining agreement applies, employees may be required to be given a fair warning as to their performance and conduct which might lead to their dismissal, as well as a step-by-step procedure leading up to dismissal.
In most instances, an employment contract will not state its expiration date. In such a case, the contract may be terminated at any time by either party. Ordinarily a contract of employment may be terminated in the same manner as any other contract. If it is to run for a definite period of time, the employer cannot terminate the contract at an earlier date without justification. If the employment contract does not have a definite duration, it is terminable at will. This is called employment at will. Under the employment at will doctrine, the employer has historically been allowed to terminate the contract at any time for any reason or for no reason. Some State Courts and some State Legislatures have changed this rule by limiting the power of the employer to discharge the employee without cause. For example, Court decisions have carved out exceptions to this doctrine when the discharge violates an established public policy, such as discharging an employee in retaliation for insisting that the employer comply with the State's Food and Drug Act.
Courts may sometimes construe an employer's statements concerning continued employment as a part of the employment contract, and therefore require good cause for the discharge of an at-will employee. Also, written personnel policies used as guidelines for the employer's supervisors have been interpreted as restricting the employer's right to discharge at-will employees without just cause. Employee handbooks or personnel manuals have been construed as part of the employee's contract.