Case C-297/07: Judgment of the Court (Second Chamber) of 11 December 2008 (reference for a preliminary ruling from the Landgericht Regensburg — Germany) — Criminal proceedings against Klaus Bourquain (Convention implementing the Schengen Agreement — Article 54 — Ne bis in idem principle — Scope — Conviction in absentia in respect of the same acts — Concept of finally disposed of — Procedural rules of national law — Concept of penalty which can no longer be enforced )