Related Rule
Denmark
Practice Relating to Rule 14. Proportionality in Attack
Denmark’s Military Criminal Code (1973), as amended in 1978, provides:
Any person who uses war instruments or procedures the application of which violates an international agreement entered into by Denmark or the general rules of international law, shall be liable to the same penalty [i.e. a fine, lenient imprisonment or up to 12 years’ imprisonment]. 
Denmark, Military Criminal Code, 1973, as amended in 1978, § 25(1).
Denmark’s Military Criminal Code (2005) provides:
Any person who deliberately uses war means [“krigsmiddel”] or procedures the application of which violates an international agreement entered into by Denmark or international customary law, shall be liable to the same penalty [i.e. imprisonment up to life imprisonment]. 
Denmark, Military Criminal Code, 2005, § 36(2).
In 2008, in a joint cost benefit analysis of a possible introduction of a national moratorium on all cluster munitions, Denmark’s Ministry of Defence and Ministry of Foreign Affairs stated:
[The] provisions, which are outlined below, are generally recognized as being an expression of customary international law. …
The purpose of international humanitarian law is to protect the victims of war as much as possible. …
[T]here are specific international legal requirements to weapons with regard to … proportionality between the military advantage of neutralising an active opposing military target and the resulting devastating consequences for the civilian population.
For military use of weapons, it is necessary to conduct a proportionality assessment between the military advantages of the attack against the expected civilian casualties. 
Denmark, Ministry of Defence and Ministry of Foreign Affairs, A Cost Benefit Analysis of a Possible Introduction of a National Danish Moratorium on All Cluster Munitions, 1 April 2008, p. 15–16.