[JURIST] Several reports out of Iraq since the outbreak of war have claimed that Iraqi forces have used civilians as involuntary "human shields" - see, for instance, this story from the Voice of America. Summing up the relevant law, a February 2003 briefing paper [text] by Human Rights Watch noted:

The use of civilians, including a state's own citizens, as human shields to protect military objectives from attack is a violation of international humanitarian law amounting to a war crime. The forcible use of civilians or other non-combatants as human shields also violates the prohibition on the taking of hostages. Customary humanitarian law and Protocol I [to the Geneva Conventions] prohibit encouraging or making use of volunteers as human shields.

The presence or movements of the civilian population or individual civilians shall not be used to render certain points or areas immune from military operations, in particular in attempts to shield military objectives from attacks or to shield, favour or impede military operations.