CIA drone campaign 'accurate and proportionate'

The most detailed database compiled so far on the accuracy of CIA drone strikes in Pakistan suggests that reports of the inaccuracy and disproportionality of civilian to military deaths are "grossly misleading", according to an article in the latest issue of the Jamestown Terrorism Monitor.
Written by three researchers at the University of Massachusetts, the article says that most of the critical reports have appeared in the Pakistani press and that they have impugned both the accuracy of the CIA drones strikes and over-estimated the number of civilian casualties.
The researchers compiled a database over the last year that draws extensively on Pakistani and Western newspaper reports of attacks, most of which are in the tribal territories along the border with Afghanistan. They only used cases where it was possible to compared multiple independent reports and always used low-end estimates for suspected militants slain. Where there was doubt, casualties were listed as 'unknown'.
According to the database, by 19 June 2010 there had been 144 confirmed CIA drone strikes in Pakistan, killing 1,372 people. Of those killed, only 68 (4.95%) were clearly identified as civilians, while 1,098 (80%) were reported to be militants or suspected militants. These included 50 high-value targets. The status of the remaining 206 deaths (15%) on the database could not be determined, so were assigned to the category 'unknown'.
The data also revealed that despite a substantial intensification of the Predator strikes starting in 2008 and accelerating through 2009 into 2010, and the broadening of target categories to include low level Pakistani Taliban, the ratio of suspected militant to civilian fatalities has remained steadily high and has gradually (if unevenly) improved.
The campaign's overall ratio of suspected militant to civilian fatalities appears to be substantially better than that of ground operations undertaken by the Pakistani Army.
The authors conclude that the CIA drone campaign is neither inefficient nor disproportionate in terms of civilian casualties. However, they note: "This conclusion does not, of course, resolve the ongoing debate over the use of Predator drones. Other objections are certainly being raised, perhaps most interestingly that their use may make going to war too easy, and thus result in a proliferation of armed conflict." The other question, not touched upon by the authors, is whether or not the drone campaign is legal under international law.