Any thug, Islam or not, can declare the issuance of a fatwa. A fatwa is non-binding, although some terrorists loudly bellow that THEIR fatwa is direct from God, Holy, binding upon all, the sins of hell, Allah peace be on him told me personally, etc................sorta' like Elmer Gantry with more hair.
Then, any council or group of self-proclaimed experts can unilaterally cancel any fatwa, with or without the original author's consent, or even knowledge.
Remember the sactity of Double Dare in grade school? As valid.