Civilians in the Geneva Convention
Two aspects of this subject that were taken from
the Encyclopedia Britannica....
Conducting hostilities - Limits on the methods and means of war - Civilians
One of the Fundamental Rules of International Humanitarian Law Applicable in Armed Conflicts, which were prepared by the International Committee of the Red Cross in 1978, requires parties to a conflict to distinguish at all times “between the civilian population and combatants in order to spare civilian population and property. Neither the civilian population as such nor civilian persons shall be the object of attack. Attacks shall be directed solely against military objectives.” Restrictions on the use of chemical or nuclear weapons against the civilian population have been discussed above. In addition, the 1981 Conventional Weapons Convention specifically prohibits the use of mines, booby traps, and other similar devices and incendiary weapons directed against the civilian population or used indiscriminately, and the first Protocol of 1977 imposes very detailed target restraints in order to protect civilians. For example, aerial bombardment engaged in for the sole purpose of terrorizing the civilian population is prohibited, and the use of aircraft to carry out such a role would therefore be illegal. Merchant ships may in limited circumstances be attacked, but they may not be sunk by a submarine without its first having placed passengers, crew, and ship’s papers in a place of safety.
  Well, where this has changed is that civilians have become the weapons, or an integral part of an adversary’s defenses, and as such, will have to become legitimate targets.
Some Improvements

Jurisdiction - Persons subject to military law - Civilians

Civilians may become subject to military jurisdiction in any number of ways. In Italy and Turkey, for example, treason or rebellion can be dealt with under the military code, and in Norway breaches by a civilian of the Geneva Conventions of 1949 and their additional Protocols of 1977 are dealt with under military law. In other countries, civilians who instigate or participate in military crimes may themselves be triable under military law. In a number of countries, civilians within a war zone or theatre of active operations, or in conditions defined as a “state of siege,” can come under military jurisdiction for offenses similar to those mentioned above—or even completely under military jurisdiction, as in Argentina.
In other countries, only civilians associated with the armed forces may be triable under service law. In Israel, for example, civilians who are employed by the army, or who have been provided with army weapons, are subject to military law, as are those held in army custody. Under British military law, civilians accompanying armed forces stationed in a foreign country (including families of soldiers as well as British civilians working for or with the services) are triable under offenses against the good order of the military community. In the United States, however, civilians—even those forming part of a service community abroad—cannot in peacetime be tried at all under the military process, though they may become subject to military jurisdiction in time of war. Austria and Spain are among countries in which no civilian can be liable to military jurisdiction.
  Well done Italy, Turkey and Norway. And coming under military jurisdiction can result in what?