In the United States, labour laws (also known as labour regulations or employment regulations) are those that serve to mediate the interaction between employees, employer entities, labour unions, and the government. Collective labour law is concerned with the three-way interaction that exists between employees, employers, and labour unions. Individual labour law is concerned with the rights of workers at work, and this is done via the contract for employment. The minimum socially acceptable circumstances under which workers or contractors are permitted to work are defined as social norms (and, in some instances, technical requirements) that must be met by all employees or contractors. Government entities (such as the old United States Employment Standards Administration) are responsible for enforcing labour regulations (legislature, regulatory, or judicial).