This article will answer to this question based on the Labor Law of Cambodia.
Employment contract is one of the contractual relations under the civil code. Many provisions on contract in the civil code are adopted pursuant to the principle of private autonomy. Accordingly, parties can choose the parties to their contracts, conclude or not to conclude the contracts, and decide the content and form of their contracts. Since workers are socially and economically inferior to the employers in the employment relation, it is more likely that workers become victim of the principle of private autonomy and the civil code is unfit with the employment relations.
The labor laws have been adopted to revise principle of private autonomy in order to ensure that workers and employers have equal stance/power in their employment relations. The labor laws provide the minimum standards or requirements of workers protection for the employment relations. For instance, the 1997 Labor Law of Cambodia, article 13, provides that the provisions of Labor law are of the nature of public order, excepting derogations provided expressly. Consequently, all rules resulted from a unilateral decision, a contract or a convention that do not comply with the provisions of the Labor Law or any legal text for its enforcement are invalid.Except for the provisions of the Labor Law that cannot be derogated in any way,the nature of public order of the Labor Law is not obstructive to the granting of benefits or the rights superior to the benefits and the rights defined in the Labor Law, granted workers by a unilateral decision of an employer or a group of employers, by an employment contract, by a collective convention or agreement, or by an arbitral decision.
In conclusion, the parties cannot agree on something different from the provisions of the Labor Law, except such differences provide workers with benefits or rights superior to those defined in the Labor Law. When parties are not sure whether their agreements provide better benefits or rights to the workers,parties mostly follow or comply with the requirements under the Labor Law.