A preliminary injunction is a court order issued prior to a final decision to either compel or restrict a party's conduct. Originating in equity and Roman law, it serves to prevent irreparable harm when traditional legal remedies are inadequate. Judges consider the probability of success on the merits, the potential for harm, the balance of equities, and the public interest. William O.
Douglas stressed the importance of such relief in situations involving irreparable damage, while Richard Posner observed that only such harm warrants a preliminary injunction. Sandra Day O’Connor pointed out that these orders are subject to less formal procedures, allowing for prompt action while maintaining the status quo. This equilibrium highlights the injunction's function in balancing individual rights with wider legal concerns.