Collective agreements, negotiated between employers and certified unions on behalf of employees, set out most of the rules governing the employment relationship. They usually have provisions dealing with rates of pay, vacations, benefits, obtaining seniority, procedures for discipline of employees, promotions, transfers and a grievance procedure.

A common feature of all collective agreements (because it is "deemed" to be there even if it is not actually in the collective agreement) is that employees many not be dismissed or otherwise disciplined except for "just and reasonable cause." Disputes over whether there was just and reasonable cause for discipline imposed by employers form much of the case work done by arbitrators. Arbitrators must determine if proper procedures were followed during the disciplinary process; whether the employee is guilty of some employment infraction justifying and discipline; and whether the discipline imposed by the employer is justified in all the circumstances. If arbitrators find that the discipline that was imposed was excessive, they have the authority to impose a lesser penalty.

Unlike non-unionized employees, employees covered by collective agreements may be reinstated to jobs they have been fired from if the arbitrator determines that there was no just and reasonable cause for dismissal. That is a very valuable right.