The European Court of Justice is hearing a case that pits Spain's data protection agency against search engine giant Google over the thorny issue of "the right to be forgotten" online.

A Spanish court sought Tuesday's hearing in Luxembourg to clarify if is subject to Spanish and European data protection laws.

In the case—one of many between Spain and Google—a person found that keying their name into Google shows a newspaper link to a property auction years ago owing to payment failure. The person wants the link removed, which the agency says Google should do. Google believes that's the newspaper's responsibility.

A ruling isn't expected for months.

If it goes in 's favor, Google could be made to erase documents people feel violate their privacy.