The requirement that an able-bodied male citizen must serve in the military forces usually takes place under the universal military training provision (as for example in Switzerland), or under emergency or war-time conscription. Compulsory military service presents a number of problems. First is the questionable effectiveness of compelling non-arms bearing citizens to become fighting or defensive forces when other options might include: an all-volunteer military; mercenaries; or, less likely, a military alliance where a particular country's role would be strictly logistic and could be fulfilled by civilians. Another difficulty is the cost to the state of compulsory training or service. The motivation of conscripts or those inducted under UMT provisions is problematical, and the disruption of private life and economic activity also can be considerable.
Compulsory military service may violate the conscience of those who object to violence, and once instituted opens the way to conscription of women and adolescents.