Here is an interesting report on US drone policy. It focuses on issues related to using them in a lethal capacity overseas. It is a good primer on facets such as blowback, forum shopping, etc.
One thing that jumped out at me while reading the Executive Summary is that it seems preemptive strikes have melded into an accepted definition of Just War theory. That issue is, however, outside of the report's scope.
http://s3.documentcloud.org/document...web-062414.pdf
Here is NY Times news of the report.
http://www.nytimes.com/2014/06/26/wo...=top-news&_r=0