Rome I and Terms of Employment
Employers who post employees abroad should check which terms of employment they should provide to them at the level required by the law of the country of posting. They should make sure whether, under the new Regulation No. 593/2008 on the Law Applicable to Contractual Obligations ("Rome I"), which came into force on 17 December
Article 8 of Rome I stipulates that if the parties choose a different applicable law than the law which would normally apply to the employment agreement, the employee will still enjoy those aspects of protection afforded to him/her by provisions of normally applicable law which according to that law cannot be derogated from by agreement. A similar but not identical rule already arises from the Rome Convention and the "Posting Directive".
Under these legal acts the employer should provide the employees with the same minimum wage, health and safety conditions, holidays, etc. as applicable under the local law.
http://www.globalemploymentlaw.com/mtc/mt-tb.cgi/801