Arguments supporting the blockade's legality
Response to armed conflict: In 2011, the UN's Palmer Report concluded that Israel's naval blockade was a legal security measure in the context of an armed conflict with Hamas, Gaza's de facto governing authority. Blockades are a recognized tactic of naval warfare, provided they meet certain conditions.
Legitimate security objective: Israel maintains that the blockade is necessary to prevent weapons, ammunition, and other military supplies from reaching militant groups in Gaza. Legal scholars supporting this view, like Ruth Wedgwood and Eric Posner, argue that the "war-like conditions" between Israel and Hamas justify the blockade under the law of armed conflict.
Effective and notified: Proponents point out that the naval blockade was formally declared and consistently enforced, and Israel provided notification via maritime alerts and diplomatic channels.
Proportionality and humanitarian access: Some legal analyses have found the blockade to be proportionate, stating that the naval component has a limited impact on the overall humanitarian situation compared to land crossings. In this view, Israel allows humanitarian aid to be transferred to Gaza through land crossings and inspected at the port of Ashdod.
UN findings:
https://unwatch.org/item-7/claim/claim-6-israels-blockade-of-gaza-is-illegal/