Member States shall confer upon the courts or administrative authorities powers enabling them in the civil or administrative proceedings provided for in Article 11:

(a) to require the trader to furnish evidence as to the accuracy of factual claims in relation to a commercial practice if, taking into account the legitimate interest of the trader and any other party to the proceedings, such a requirement appears appropriate on the basis of the circumstances of the particular case;

and

(b) to consider factual claims as inaccurate if the evidence demanded in accordance with (a) is not furnished or is deemed insufficient by the court or administrative authority.