Luxembourg

In case of international crisis, or of real threats to the vital interests of all or part of the population or of imminent danger resulting from grave infringement of public security, the Grand Duke, after having declared urgency resulting from the impossibility of the chamber of deputies to legislate in the appropriate time periods, may take regulatory measures in all matters.
These measures may derogate from existing laws. They must be necessary, appropriate and proportionate to the goal pursued and be in conformity with the Constitution and with the international treaties. 
... (Art. 48)

The provisions of the Constitution do not block the obligations deriving from the Statute of the International Criminal Court. (Art. 111)

…
(8) The provisions of the laws declared non-conforming to the Constitution by an order [arret] of the Constitutional Court cease to have a juridical effect the day after the publication of this order in the forms specified by the law, unless the Constitutional Court ordered another time [délai]. The Constitutional Court determines the conditions and limits within which the effects that the provision produces are susceptible to be questioned. (Art. 112)

No provision of the Constitution may be suspended. (Art. 130)