A SYSTEM IS NOT NECESSARILY DISCRIMINATORY SIMPLY BECAUSE ONE OF ITS CRITERIA MAKES REFERENCE TO ATTRIBUTES MORE CHARACTERISTIC OF MEN . IN ORDER FOR A JOB CLASSIFICATION SYSTEM AS A WHOLE TO BE NON-DISCRIMINATORY AND THUS TO COMPLY WITH THE PRINCIPLES OF THE DIRECTIVE , IT MUST , HOWEVER , BE ESTABLISHED IN SUCH A MANNER THAT IT INCLUDES , IF THE NATURE OF THE TASKS IN QUESTION SO PERMITS , JOBS TO WHICH EQUAL VALUE IS ATTRIBUTED AND FOR WHICH REGARD IS HAD TO OTHER CRITERIA IN RELATION TO WHICH WOMEN WORKERS MAY HAVE A PARTICULAR APTITUDE .
16 IT IS FOR THE NATIONAL COURTS TO DETERMINE ON A CASE-BY-CASE BASIS WHETHER A JOB CLASSIFICATION SYSTEM AS A WHOLE ALLOWS PROPER ACCOUNT TO BE TAKEN OF THE CRITERIA NECESSARY FOR ADJUSTING PAY RATES ACCORDING TO THE CONDITIONS REQUIRED FOR THE PERFORMANCE OF THE VARIOUS DUTIES THROUGHOUT THE UNDERTAKING .
17 THE ANSWER TO QUESTION ( 1 ) MUST THEREFORE BE THAT COUNCIL DIRECTIVE 75/117 OF 10 FEBRUARY 1975 ON THE APPROXIMATION OF THE LAWS OF THE MEMBER STATES RELATING TO THE APPLICATION OF THE PRINCIPLE OF EQUAL PAY FOR MEN AND WOMEN DOES NOT PROHIBIT THE USE , IN A JOB CLASSIFICATION SYSTEM FOR THE PURPOSE OF DETERMINING RATES OF PAY , OF THE CRITERION OF MUSCLE DEMAND OR MUSCULAR EFFORT OR THAT OF THE HEAVINESS OF THE WORK IF , IN VIEW OF THE NATURE OF THE TASKS INVOLVED , THE WORK TO BE PERFORMED DOES REQUIRE THE USE OF A CERTAIN DEGREE OF PHYSICAL STRENGTH , SO LONG AS THE SYSTEM AS A WHOLE , BY TAKING INTO ACCOUNT OTHER CRITERIA , PRECLUDES ANY DISCRIMINATION ON GROUNDS OF SEX .
QUESTIONS ( 2 ) AND ( 3 )
18 IT APPEARS FROM THE WORDING OF THOSE QUESTIONS AND FROM THE GROUNDS OF THE ORDER FOR REFERENCE THAT THE NATIONAL COURT WISHES IN SUBSTANCE TO KNOW WHETHER , IN THE EVENT THAT THE CRITERIA OF MUSCLE DEMAND OR MUSCULAR EFFORT AND OF THE HEAVINESS OF THE WORK ARE COMPATIBLE WITH DIRECTIVE 75/117 , THE FACT THAT IN DETERMINING TO WHAT EXTENT WORK REQUIRES AN EFFORT OR IS DEMANDING OR HEAVY , REGARD IS HAD TO THE DEGREE TO WHICH THE WORK REQUIRES AN EFFORT OR IS DEMANDING OR , FOR WOMEN WORKERS , SATISFIES THE REQUIREMENTS OF THE DIRECTIVE .
19 THE DEFENDANT ARGUES THAT REGARD MUST BE HAD ONLY TO THE OBJECTIVE NATURE OF THE WORK TO BE CARRIED OUT AND THE OBJECTIVELY MEASURABLE DEMANDS IT MAKES .
20 THE UNITED KINGDOM ADDS THAT TO USE AN ABSOLUTE LEVEL OF MUSCULAR EFFORT OR AN ABSOLUTE DEGREE OF HEAVINESS OF THE WORK , WHICH IN FACT AMOUNTS TO USING MALE POINTS OF REFERENCE , CAN CONSTITUTE NO MORE THAN INDIRECT DISCRIMINATION , WHICH IS NOT PROHIBITED BY ARTICLE 119 OF THE EEC TREATY IN SO SO FAR AS IT IS BASED ON OBJECTIVELY JUSTIFIABLE GROUNDS . SUCH GROUNDS EXIST WHERE AN EMPLOYER MUST , IN ORDER TO ATTRACT