A combatant (also referred to as an enemy combatant) is a soldier or guerrilla member who is waging war. Under the Geneva Conventions, persons waging war must have the following four characteristics to be protected by the laws of war:
He leaves out a fifth:
Article4, clause 6
Inhabitants of a non-occupied territory, who on the approach of the enemy spontaneously take up arms to resist the invading forces, without having had time to form themselves into regular armed units, provided they carry arms openly and respect the laws and customs of war.
If an Afghan heard the Americans were coming, took his rifle, and started taking pot shots out of his bedroom window, he is entitled to prisoner of war status upon capture.
If he did the same the day after the Americans had arrived, he isn't.
A captured person not wearing a uniform who is caught carrying weapons or engaging in warlike acts (such as a spy) is not a lawful combatant and is therefore not protected by the laws of war.
This is completely and utterly wrong.
If he doesn't qualify as a POW, he is a civilian, entitled to protection under the (Fourth) Geneva Convention relative to the Protection of Civilian Persons in Time of War)
The Fourth Convention has specific clauses relating to a person not in uniform carrying out warlike acts.
In particular:
Article 5
Where, in the territory of a Party to the conflict, the latter is satisfied that an individual protected person is definitely suspected of or engaged in activities hostile to the security of the State, such individual person shall not be entitled to claim such rights and privileges under the present Convention as would, if exercised in the favour of such individual person, be prejudicial to the security of such State.
Where in occupied territory an individual protected person is detained as a spy or saboteur, or as a person under definite suspicion of activity hostile to the security of the Occupying Power, such person shall, in those cases where absolute military security so requires, be regarded as having forfeited rights of communication under the present Convention.
In each case, such persons shall nevertheless be treated with humanity, and in case of trial, shall not be deprived of the rights of fair and regular trial prescribed by the present Convention. They shall also be granted the full rights and privileges of a protected person under the present Convention at the earliest date consistent with the security of the State or Occupying Power, as the case may be.
Note how, even if they have carried out hostile acts, they are still calssified as protected persons under the convention.
Article 68
Protected persons who commit an offence which is solely intended to harm the Occupying Power, but which does not constitute an attempt on the life or limb of members of the occupying forces or administration, nor a grave collective danger, nor seriously damage the property of the occupying forces or administration or the installations used by them, shall be liable to internment or simple imprisonment, provided the duration of such internment or imprisonment is proportionate to the offence committed. Furthermore, internment or imprisonment shall, for such offences, be the only measure adopted for depriving protected persons of liberty. The courts provided for under Article 66 of the present Convention may at their discretion convert a sentence of imprisonment to one of internment for the same period.
The penal provisions promulgated by the Occupying Power in accordance with Articles 64 and 65 may impose the death penalty on a protected person only in cases where the person is guilty of espionage, of serious acts of sabotage against the military installations of the Occupying Power or of intentional offences which have caused the death of one or more persons, provided that such offences were punishable by death under the law of the occupied territory in force before the occupation began.
The death penalty may not be pronounced against a protected person unless the attention of the court has been particularly called to the fact that, since the accused is not a national of the Occupying Power, he is not bound to it by any duty of allegiance.
In any case, the death penalty may not be pronounced against a protected person who was under eighteen years of age at the time of the offence.
Article 70
Protected persons shall not be arrested, prosecuted or convicted by the Occupying Power for acts committed or for opinions expressed before the occupation, or during a temporary interruption thereof, with the exception of breaches of the laws and customs of war.
Nationals of the Occupying Power who, before the outbreak of hostilities, have sought refuge in the territory of the occupied State, shall not be arrested, prosecuted, convicted or deported from the occupied territory, except for offences committed after the outbreak of hostilities, or for offences under common law committed before the outbreak of hostilities which, according to the law of the occupied State, would have justified extradition in time of peace.
Article 71
No sentence shall be pronounced by the competent courts of the Occupying Power except after a regular trial.
Accused persons who are prosecuted by the Occupying Power shall be promptly informed, in writing, in a language which they understand, of the particulars of the charges preferred against them, and shall be brought to trial as rapidly as possible. The Protecting Power shall be informed of all proceedings instituted by the Occupying Power against protected persons in respect of charges involving the death penalty or imprisonment for two years or more; it shall be enabled, at any time, to obtain information regarding the state of such proceedings. Furthermore, the Protecting Power shall be entitled, on request, to be furnished with all particulars of these and of any other proceedings instituted by the Occupying Power against protected persons.
Article 72
Accused persons shall have the right to present evidence necessary to their defence and may, in particular, call witnesses. They shall have the right to be assisted by a qualified advocate or counsel of their own choice, who shall be able to visit them freely and shall enjoy the necessary facilities for preparing the defence.
Failing a choice by the accused, the Protecting Power may provide him with an advocate or counsel. When an accused person has to meet a serious charge and the Protecting Power is not functioning, the Occupying Power, subject to the consent of the accused, shall provide an advocate or counsel.
Accused persons shall, unless they freely waive such assistance, be aided by an interpreter, both during preliminary investigation and during the hearing in court. They shall have the right at any time to object to the interpreter and to ask for his replacement.
Article 73
A convicted person shall have the right of appeal provided for by the laws applied by the court. He shall be fully informed of his right to appeal or petition and of the time limit within which he may do so.
Article 75
In no case shall persons condemned to death be deprived of the right of petition for pardon or reprieve.
No death sentence shall be carried out before the expiration of a period of at least six months from the date of receipt by the Protecting Power of the notification of the final judgment confirming such death sentence, or of an order denying pardon or reprieve.
The six months period of suspension of the death sentence herein prescribed may be reduced in individual cases in circumstances of grave emergency involving an organized threat to the security of the Occupying Power or its forces, provided always that the Protecting Power is notified of such reduction and is given reasonable time and opportunity to make representations to the competent occupying authorities in respect of such death sentences.
Article 76
Protected persons accused of offences shall be detained in the occupied country, and if convicted they shall serve their sentences therein. They shall, if possible, be separated from other detainees and shall enjoy conditions of food and hygiene which will be sufficient to keep them in good health, and which will be at least equal to those obtaining in prisons in the occupied country.
They shall receive the medical attention required by their state of health.
They shall also have the right to receive any spiritual assistance which they may require.
Women shall be confined in separate quarters and shall be under the direct supervision of women.
Proper regard shall be paid to the special treatment due to minors.
Protected persons who are detained shall have the right to be visited by delegates of the Protecting Power and of the International Committee of the Red Cross, in accordance with the provisions of Article 143.
Such persons shall have the right to receive at least one relief parcel monthly.
Article 77
Protected persons who have been accused of offences or convicted by the courts in occupied territory shall be handed over at the close of occupation, with the relevant records, to the authorities of the liberated territory.
The Geneva Convention goes into a lot of detail about what can be done to civilians who engage in attacks on occupying forces. How that equates to them not being protected, when there is so much in the convention about exactly how they may be treated, I don't know.
Geneva Convention relative to the Treatment of Prisoners of War
http://www.unhchr.ch/html/menu3/b/91.htmGeneva Convention relative to the Protection of Civilian Persons in Time of War
http://www.unhchr.ch/html/menu3/b/92.htm