Burden of proof
Burden of proof refers to the obligation or responsibility to prove, in a case before the courts, the assertions made by a complainant. The general rule is that the burden of proof lies with the party who makes the allegation.
National courts dealing with complaints of discrimination have applied different procedural rules to deal with the practical difficulties resulting from the burden of providing evidence. In a number of cases, the European Court of Justice has sought to address the problem by reversing the burden of proof, requiring the employer to prove that a particular practice is not discriminatory (e.g. Handels-og Kontorfunktionaerernes Forbund i Danmark v. Dansk Arbejdsgiverforening (acting for Danfoss), Case 109/88,  ECR 3199); Enderby v. Frenchay Area Health Authority, Case 127/92  ECR 5535). The rule was codified in Council Directive 97/80/EC on the burden of proof in cases of discrimination based on sex (Article 4(1)).
Once the complainant has provided a prima facie case of sex discrimination, the burden of proof switches to the respondent. Identical provisions can be found in Directives concerned with discrimination on other grounds (see, for example, Council Directive 2000/43 implementing the principle of equal treatment between persons irrespective of racial or ethnic origin); and Council Directive 2000/78 establishing a general framework for equal treatment in employment and occupation).