In August of
2016, the American Civil Liberties Union (ACLU) was successful in getting the
White House to declassify the PRESIDENTIAL POLICY GUIDANCE: White House
Rules on Targeted Killing document, which explains the framework for drone

According to
the ACLU:

response to a court order in a lawsuit filed by the American Civil Liberties
Union, the Obama administration has released a redacted version of the White
House document that sets out the government’s policy framework for drone
strikes “outside the United States and areas of actual hostilities.” 

Presidential Policy Guidance, once known as “the Playbook,” was issued by
President Obama in May 2013 following promises of more transparency and
stricter controls for the drone program. But while the administration released
a short “fact sheet” describing the document, it did not release the PPG
itself, or any part of it.

Declassified Presidential Policy Guidance

POLICY GUIDANCE: White House Rules on Targeted Killing With Drones
Pages, 2.7MB]