Luxembourg

The Council of State gives its opinion on the bills and proposals of law as well as on the amendments which might be proposed.
If it considers that a bill or proposal of law includes provisions which are nonconform with the Constitution, with the international treaties to which the Grand Duchy of Luxembourg is a party, with the juridical acts of the European Union or with the general principles of law [droit], it mentions it in its opinion.
... (Art. 95)

(1) The Constitutional Court decides, by means of [an] order [arret], on the conformity of laws with the Constitution.
(2) The Constitutional Court may be referred to [a matter], under title of preliminary opinion [titre prejudiciel], following the modalities to be determined by the law, by any jurisdiction to decide on the conformity of the laws, with the exception of the laws concerning approval of treaties, with the Constitution.
(3) The Constitutional Court will regulate the disputes of attribution according to the mode determined by the law.
(4) The attributions of the Constitutional Court may be extended by a law voted by a qualified majority gathering at least two-thirds of the votes of the members of the chamber of deputies, the vote by proxy not being admitted.
... (Art. 112)