Surreptitious advertising refers to secretive communication practices that might mislead the public about products or services.
An old EU Directive, the Television Without Frontiers (TWF) Directive, said that misleading representations of products are considered intentional "in particular if it is done in return for payment or for similar consideration".
The TWF Directive has since been replaced by the EU Audiovisual Media Services Directive which contains an identical qualification, meaning the ECJ ruling is relevant to broadcasters today.
The ECJ said that provisions within the TWF Directive do not mean TV companies have to have received payment or a similar perk for intentional surreptitious advertising practices to be proven.
"[The TWF Directive's provisions] should not be so narrowly construed that such a representation may be regarded as intentional only if it is done in return for payment or for similar consideration," the ECJ said in its ruling.
"Neither the wording of the presumption established in [the TWF Directive] nor the purpose and general scheme of [TWF Directive] support such an interpretation," the ECJ said.
"On the contrary, such an interpretation could undermine the full and proper protection of the interests of television viewers – as sought by [the TWF Directive], in particular through the prohibition of surreptitious advertising ... and, furthermore, could deprive that prohibition of its effectiveness, given the difficulty, or even the impossibility, in certain cases of proving that there has been provision of payment or of consideration of another kind for advertising which nevertheless displays all the characteristics ... of surreptitious advertising," the ECJ ruling said.
Greek courts had asked the ECJ to consider whether payment or a similar consideration was a required condition for proving TV companies intentionally engaged in surreptitious advertising. The courts' referral came following disputes about rules governing the practices laid out in Greek law.
The words "in particular" that qualify that payment or other considerations are examples of proof of intentional surreptitious advertising practice are omitted from the Greek laws implementing the TWF Directive, the ECJ ruling said.
The Greek courts are currently considering whether it was right for a regulator to fine a TV company for endorsing a dental treatment, the ECJ ruling papers said. The alleged endorsements took place in November 2003 when the TWF Directive was still effective. The AVMS Directive was established in 2007.