Israeli negotiations to free Palestinian terrorists from prison, in exchange for an Israeli soldier (Gilad Shalit) seized on the Gaza border three years ago, revealed that 65 percent of terrorists freed in earlier exchanges subsequently returned to terrorist activities. Under these circumstances, it is more difficult for Israel to release Palestinians. This, despite the fact that the released prisoners are supposed to promise to no longer engage in terrorist activities, or go into exile.
The recidivism numbers came from an Israeli study of past exchanges. In 2004, Israel released 436 prisoners in exchange for a kidnapped Israeli civilian, and in 1982 1,150 were released for three Israeli soldiers.
Currently, Hamas is demanding up to 1,400 terrorists in return for the Israeli soldier they hold. But based on past experience, this would put over 700 terrorists back to work. That, based on past experience, will result in over a dozen Israelis dead in future terrorist attacks. Still, Israel is willing to make a lopsided exchange, but not as lopsided as Hamas demands.