Many instances exist where the age limits or various exemption possibilities apply only in time of peace, or are modified in time of war.
In Greece, for example, in peacetime call-up may take place from the beginning of the year in which the conscript becomes 19, but in time of mobilisation Article 1 of Law 2510/1997 lowers this age by a year, and Article 14 permits the Minister of Defence to authorise the recruitment of volunteers a year before they would be subject to conscription. As it happens, Greece has been in a permanent state of mobilisation since 1976, although it is not clear whether advantage has in practice been taken of these provisions.
Article 2 of the Militia Act (1962) in Belgium, permits conscripts to be called up
in time of war or a threat to the territory, from 1st January of the year in which they become 17. In both Estonia (Article 124 of the Constitution) and Kyrgystan (Article 20 of the 1998 ‘Law on mobilisation preparation and mobilisation in the Kyrgyz Republic,’) make citizens over 16 subject to military service in time of mobilisation. A similar provision in Mozambique was criticised by the Committee on the Rights of the Child. Not only does the
Optional Protocol to the Convention on the Rights of the Child on the Involvement of Children in Armed Conflict contain an absolute prohibition on the conscription of under-18s; ILO Convention 182 on the Worst Forms of Child Labour which has been even more widely ratified (including by the States cited as examples above) bans the
forced or compulsory recruitment of children for use in armed conflict. Such legal provisions to lower the conscription age in wartime, or when war is imminent, would thus lead most States into direct breaches of their treaty obligations, were they actually to be implemented.
Women may be conscriptable in war - though generally not for active service. This is for instance the case in Paraguay and Brazil. Brazil is also one of the States where the exemption of the clergy from military service does not apply in time of war:
Women and members of the clergy are exempt from military service in times of peace, although they are subject to other obligations set out in law. Many Vatican Concordats with States allow the exemption of priests from military service in time of peace, but permit their recruitment for unarmed service as chaplains or medical assistants in time of war or general mobilisation.
In Sweden, under the Act on Liability for Total Defence Service,
The supply of personnel for the Total Defence shall be secured by a liability for Total Defence for each Swedish citizen from the beginning of the year when he or she becomes 16 years old until the end of the year when he or she becomes 70 years old. The obligation is also valid for each person living in Sweden without Swedish citizenship. This liability involves
military, civilian, or general service. The military and civilian service includes basic training, refresher training, readiness service and wartime service. The general service implies that a person who is liable for Total Defence is obliged to serve during increased readiness...
-  Concluding observations of the Committee on the Rights of the Child: Mozambique, UN Document CRC/C/15/Add.172, 3 April 2002, paragraph 23 (c).
-  Romania, on the other hand, which according to the Child Soldiers Global Report 2004 has a provision to lower the conscription age from 20 to 18 in time of war, would be able to implement this without implications for its treaty obligations.
-  Brazil's Declaration to accompany its ratification of the Optional Protocol to the Convention on the Rights of the the Child on the involvement of children in armed conflict.
-  Act on Liability for Total Defence Service, 1809/1994, Paragraph 1.2
-  Ibid., paragraph 1.4