Working conditions are established for all workers, as laid down in Article 3 of the Workers' Statute, via the labour relations instruments, i.e. national legislative provisions, collective agreements, the agreement of both parties as set out in the work contract, which must not contain conditions which are less favourable to the worker or which conflict with the provisions and collective agreements referred to above, or, in the absence of such, customary local practice the occupation concerned, except by express derogation.
Las condiciones de trabajo se definen, para la generalidad de los trabajadores, de acuerdo con lo establecido en el artículo 3 del Estatuto de los Trabajadores, por las fuentes de la relación laboral, esto es: por los convenios colectivos, por la voluntad de las partes, manifestada en el contrato