"1949年《日内瓦四公约》禁止劫持人质，并通过条款禁止一方“不积极参加敌对行动”损害其控制下的人员，禁止使用人盾。"

https://www.cia.gov/library/reports/general-reports-1/iraq_human_shields/index.html

The four Geneva Conventions of 1949 prohibit the taking of hostages and ban the use of human shields through clauses that forbid a party from harming those in its control "not actively taking part in hostilities."