Industrial action by employees has always been a particularly contentious aspect of the industrial relations process.
In legal terms, virtually all such action is unlawful. This means that, theoretically at least, those who organise or participate in it would be exposed to liability in contract and/or tort, and under statute. This would place workers and workers and unions in a very vulnerable position in the context of collective bargaining, and helps explain why most common law jurisdictions have introduced some form of statutory protection against legal exposure in connection with organising or participating in industrial action.
The principal form of employer industrial action is the lockout: that is, the exclusion of all or part of the workforce from the workplace, either as a pre-emptive tactic to exert pressure upon employees/unions with whom the employer is in dispute, or as retaliation for some form of industrial action (such as a partial work-ban) undertaken by employees.
Employer industrial tactics can also include: withdrawal of work-related benefits, especially those that are non-contractual in character; denial of access to overtime or discretionary bonus payments; disciplinary action against, or dismissal of, employees who participate in industrial action; engagement of replacement workers; outsourcing of particular business functions; cancellation, or threatened cancellation, of proposed investment; and closure, or threatened closure, of all or part of a plant.
Unlike worker industrial action, most of these tactics would be quite lawful at common law — although there are now statutory provisions which would render some of them unlawful in some circumstances (eg termination of the employment of workers who participated in lawful industrial action).
See Liability in contract and tort.