In the employment context, a lockout occurs when management shuts down company operations to prevent union workers from working. It is a tactic typically used by employers to hinder union organization or to gain leverage in labour disputes. Although it may entail locking employees out of the workplace, but it can also be achieved through work stoppage, layoffs, or the hiring of nonunion replacement workers. Lockouts have generally been regarded as legal by the courts, although in some cases they have been held unlawful if they violate the terms of a joint agreement.
Lockout may also refer to the practices and procedures necessary to disable machinery or equipment in order to prevent the release of hazardous energy while employees perform servicing and maintenance activities.