In the present case, the Court emphasized the importance of the guarantee to challenge the lawfulness of one's detention. The Court also stated that the review process has to ensure the review of lawfulness not only in accordance with national law but also the Convention.
For the review process to be lawful, the Court outlined the following requirements:
The reviewing 'court' must have competence to decide on the lawfulness of detention and order release if the detention is unlawful.
As to the process, the procedural guarantees do not necessarily need to correspond to those required by the right to a fair trial under Article 6 of the Convention. However, the process must have judicial character and ensure safeguards for the type of deprivation of liberty in question. For instance, the proceedings must be adversarial and ensure 'equality of arms'. In order to allow the detainee to challenge the grounds of detention, witnesses might be heard and access to the necessary case documents ensured.
There may be restrictions on the right to a fully adversarial procedure where strictly necessary in the light of a strong countervailing public interest, such as national security, the need to keep secret certain police methods of investigation or the protection of the fundamental rights of another person. However, any difficulties caused to the defendant by a limitation on his rights must be sufficiently counterbalanced by the procedures followed by the judicial authorities.