The chapter analyzes the complex system of labour law sanctions against unlawful violations of employee obligations, consisting of statutory laws, collective agreements, agreements of the parties and unilateral sources issued by the employer. The chapter looks at various forms of liability of the employee, and the responsibilities of the employer are discussed in detail. The employer may use disciplinary measures extending from warning and disciplinary sanctions to termination of employment. However, the employer and the employee may be liable for third-party damages and fines by public authorities, which must be paid in accordance with national rules. The chapter discusses opportunities and weaknesses of labour law in the particular context of cartels and antitrust rules. The author concludes that as regards sanctions against rogue employees for cartel actions, the employer has several choices depending on the strength of the sanction and its legal nature. Labour law focuses primarily on the protection of employees in these fields, but the employer is also entitled to proper protection against unlawful activities of rogue employees in case of cartel actions.