Most of them doesn't have any charges on them. One night their houses raided in WB or Gaza and put in jail. And there are also minors. Most of those people are not captured during a "war". Their imprisonment is illegal. On the other hand you should know 2 things about Geneva Convention. It prohibits torture&intimidation against prisoner, that Israel does constantly and if your prisoners are not treated by convention, the world doesn't seek you to follow it. So, Israel keeps torturing innocent Arab minors, how can you expect Hamas to follow the convention?
Swiss customs seize 578 pounds of ivory en route to China (AP)
from the article: Report: Israel-Hamas talks on Shalit deal delayed indefinitely