By its judgment of 12 July 2013 (LJN: BZ3640), the Supreme Court confirmed that "will-dependent" material cannot be used to impose punitive sanctions. Persons can only be compelled to provide such material to a government authority with the explicit guarantee that it will not be used to impose a punitive sanction.

The case is relevant from a competition law perspective as the Dutch Supreme Court confirms the limits of the duty to provide information and to cooperate with government authorities. While authorities like the Authority for Consumers and Markets ("ACM") have broad powers and can levy heavy fines for non-cooperation, their powers are limited by the rights of defence as enshrined in, inter alia, Article 6 ECHR. The Supreme Court decision provides an authoritative confirmation that Article 6 ECHR and the case-law of the European Court of Human Rights ("ECtHR") have to be interpreted in such a way that Dutch government authorities cannot compel a person to submit will-dependent material without the guarantee that the material cannot be used to impose a punitive sanction on that person. If the ACM requests undertakings for information on the basis of its general monitoring and enforcement powers before opening an investigation, undertakings could demand the ACM to guarantee that any will-dependent materials provided cannot be used to impose punitive sanctions on it.

The case revolves around a dispute between an unidentified private individual, who appealed in cassation ("Appellant"), and the Dutch tax authority. The Supreme Court discusses the relationship between an individual's duty to provide the tax authority with all relevant information for that individual's taxation and the right against self-incrimination as guaranteed by Article 6 ECHR.

A lower court had, at the request of the tax authority, ordered Appellant to provide information about his foreign bank account and income. Appellant claimed that the order violated his right against self-incrimination as protected by Article 6 ECHR, since at least part of the requested information qualified as will-dependent materials within the meaning of the Saunders judgment of the ECtHR (Saunders v. the United Kingdom). Since Appellant could not exclude that the information would be used against him to impose a punitive sanction, he claimed that he could not be compelled to hand over that information.

The Supreme Court recalled the Saunders judgment and made a distinction between (i) information that exists independent of the will of the person concerned; and (ii) information that does not exist independent of the will of the person concerned, that is, "will-dependent" material. It ruled that a person can be compelled to submit both types of information for taxation purposes but the second type of information cannot be used to impose a punitive sanction on that person.