(25) The prohibition of age discrimination is an essential part of meeting the aims set out in the Employment Guidelines and encouraging diversity in the workforce. However, differences in treatment in connection with age may be justified under certain circumstances and therefore require specific provisions which may vary in accordance with the situation in Member States. It is therefore essential to distinguish between differences in treatment which are justified, in particular by legitimate employment policy, labour market and vocational training objectives, and discrimination which must be prohibited. (26) The prohibition of discrimination should be without prejudice to the maintenance or adoption of measures intended to prevent or compensate for disadvantages suffered by a group of persons of a particular religion or belief, disability, age or sexual orientation, and such measures may permit organisations of persons of a particular religion or belief, disability, age or sexual orientation where their main object is the promotion of the special needs of those persons. (27) In its Recommendation 86/379/EEC of 24 July 1986 on the employment of disabled people in the Community(7), the Council established a guideline framework setting out examples of positive action to promote the employment and training of disabled people, and in its Resolution of 17 June 1999 on equal employment opportunities for people with disabilities(8), affirmed the importance of giving specific attention inter alia to recruitment, retention, training and lifelong learning with regard to disabled persons. (28) This Directive lays down minimum requirements, thus giving the Member States the option of introducing or maintaining more favourable provisions. The implementation of this Directive should not serve to justify any regression in relation to the situation which already prevails in each Member State. (29) Persons who have been subject to discrimination based on religion or belief, disability, age or sexual orientation should have adequate means of legal protection. To provide a more effective level of protection, associations or legal entities should also be empowered to engage in proceedings, as the Member States so determine, either on behalf or in support of any victim, without prejudice to national rules of procedure concerning representation and defence before the courts. (30) The effective implementation of the principle of equality requires adequate judicial protection against victimisation. (31) The rules on the burden of proof must be adapted when there is a prima facie case of discrimination and, for the principle of equal treatment to be applied effectively, the burden of proof must shift back to the respondent when evidence of such discrimination is brought. However, it is not for the respondent to prove that the plaintiff adheres to a particular religion or belief, has a particular disability, is of a particular age or has a particular sexual orientation. (32) Member States need not apply the rules on the burden of proof to proceedings in which it is for the court or other competent body to investigate the facts of the case. The procedures thus referred to are those in which the plaintiff is not required to prove the facts, which it is for the court or competent body to investigate. (33) Member States should promote dialogue between the social partners and, within the framework of national practice, with non-governmental organisations to address different forms of discrimination at the workplace and to combat them. (34) The need to promote peace and reconciliation between the major communities in Northern Ireland necessitates the incorporation of particular provisions into this Directive. (35) Member States should provide for effective, proportionate and dissuasive sanctions in case of breaches of the obligations under this Directive. (36) Member States may entrust the social partners, at their joint request, with the implementation of this Directive, as regards the provisions concerning collective agreements, provided they take any necessary steps to ensure that they are at all times able to guarantee the results required by this Directive. (37) In accordance with the principle of subsidiarity set out in Article 5 of the EC Treaty, the objective of this Directive, namely the creation within the Community of a level playing-field as regards equality in employment and occupation, cannot be sufficiently achieved by the Member States and can therefore, by reason of the scale and impact of the action, be better achieved at Community level. In accordance with the principle of proportionality, as set out in that Article, this Directive does not go beyond what is necessary in order to achieve that objective, HAS ADOPTED THIS DIRECTIVE: CHAPTER I GENERAL PROVISIONS Article 1