A post-contractual non-compete clause is only valid if it has been agreed in writing and the employee had insight into the customer base or into manufacturing and trade secrets whose use could cause the employer substantial harm.
The prohibition must be reasonably limited in terms of place, time and subject matter. More than three years is permissible only in special circumstances, and the court can restrict an excessive prohibition. The prohibition lapses if the employer terminates without justified reason or if the employee terminates for a justified reason attributable to the employer.