In the world of principle and international law, the ongoing Israeli blockade of Gaza - which until now blocks Gazans from traveling to the West Bank and East Jerusalem, and blocks Gazans from exporting, farming, fishing, and otherwise earning their living - is a clear violation of the Fourth Geneva Convention, which bars the use of "collective punishment" against a civilian population living under occupation.
The International Committee of the Red Cross - a key guardian of the Fourth Geneva Convention - has stated this clearly. As Voice of America reported:
"The International Committee of the Red Cross says Israel's blockade of the Gaza Strip breaks international law. The humanitarian agency said Monday that the blockade violates the Geneva Convention, which bans 'collective punishment' of a civilian population. "
Article 33 of the Fourth Geneva Convention of 1949 - on the Red Cross website - says: "No protected person may be punished for an offence he or she has not personally committed. Collective penalties and likewise all measures of intimidation or of terrorism are prohibited...Reprisals against protected persons and their property are prohibited."
"Protected persons" are defined in Article 4: "Persons protected by the Convention are those who, at a given moment and in any manner whatsoever, find themselves, in case of a conflict or occupation, in the hands of a Party to the conflict or Occupying Power of which they are not nationals."