According to news reports, Jordan is threatening to hasten the execution of terrorists in retaliation if daesh kills Jordanian hostage Moaz al-Kaseasbeh. That is, Jordan's treating its own prisoners as hostages in some respects.
Apart from the application of the death penalty, and potential issues relating to the fairness of trials, are there any theoretical human rights that could be violated as a result of this action? For example, would it be seen as collective punishment? This was answered on Law.SE for the current legal rights.