https://ecf.dcd.uscourts.gov/cgi-bin/show_public_doc?2012cv1...
It's an interesting read, but part of the argument was that there were Congressional checks and balances in place for security threat review and congress authorized force against the group in question which essentially gave the executive branch authority to add the specific targets in question.
The legality of the disposition matrix at large can still be tested and re-tested depending on the specific actions of the executive branch.
