2.3.1. Duty of Mutual Assistance and Co-operation

In its wording, Article 10 EC contains three obligations: Member States shall take all

general and specific measures to ensure fulfilment of obligations arising from Community

law and to facilitate the achievement of the Community's tasks; and Member

States shall abstain from any measure which could jeopardise the attainment of the

Treaty's objectives. Underlying these obligations is a general duty of co-operation

which goes beyond the exact wordings of the provisions.1 ' ' Although addressed to the

Member States, the duty of co-operation is not cast on the Member States alone. The

Community Institutions, and in particular the Commission, are also bound by a duty

of sincere co-operation. Furthermore, the duty of co-operation also applies horizon

tally; that is, it does not only operate between the Community and the Member States

but also between the Institutions and the Member States inter sc.

The principles and duties under Article 10 EC are essential to the Community legal

order. In the Community legal order Member States enjoy wide powers, and the Community

depends to large extent on having its policies carried out by the Member

States.1 1 1 Article 10 EC is to ensure the full efficacy of Community law. In this sense,

the duties for the Member States were not exhausted in the Treaty but 'the Member

States continue beyond that to have a binding responsibility for the further development

of the Communities which represents a real legal o b l i g a t i o n ' . 1 " Of course,

Article 10 EC is not a panacea and clearly the Court will not 'heed every call to advance

the C o m m u n i t y ' o n the basis of Article 10 EC alone. At the same time ' o n e must avoid

the failure of imagination which would follow from allowing its value to be hidden

by the diverse fact situations in which it appears'. " Rather one should try to 'trace

stimuli in the Court's approach to Article 5 I now 10) which might yield indications

of the realistic potential' of that provision.'

The duty of assistance and co-operation in good faith which Member States owe to

each other under Community law is particularly clear in the Court's judgments in

Mattencci'and Alliamisopoulos.'''" In the former the Court declared that pursuant to

Article 10 EC

every Member State is under a duty to facilitate the application of |aj provision

[of Community law] and, to that end, to assist every other Member State which

is under an obligation under Community law.1 '

In its judgment in Athannsopoulos the Court held that under Article 10 EC

the Member States in which a person claiming a benefit supplement is residing

are bound by a duly to cooperate in good faith with the institutions of the other

Member States which are responsible for ensuring the performance of the obligations

arising out of Regulation No 1408/71.'"'

A duty of mutual assistance and co-operation in good faith has considerable potential

and should not be underestimated. However, the above judgments also indicate important

limits to that potential. The duty relates to giving full effect to Community

law and attaining its objectives and policies but does not become operative by virtue

of a Member State pursuing its own national interests."' The question for the present

purposes thus becomes whether and, if so under what conditions, according effect to

measures of sister Member States contributes to the full implementation of C o m m u nity

law and policies. In examining this question further, it should be kept in mind

that the question only arises in respect of rules of mandatory law that may be applied

in conformity with Community law; a measure must be justified as being necessary

and proportionate for the protection of mandatory requirements, or it may not be

applied at all.