The U.S. Senate needs to examine thoroughly John Brennan, whom President Barack Obama nominated to succeed David H. Petraeus as director of the Central Intelligence Agency. Brennan, who since 2009 has served as Obama's chief counter-terrorism advisor, was deputy executive director of the CIA when the George W. Bush administration and the CIA designed an interrogation program for suspected al-Qaida prisoners that included waterboarding and other "enhanced interrogation techniques." Many current and former CIA officers say Brennan wasn't deeply involved in the program. Brennan himself, in a 2008 letter wrote that he was "a strong opponent" of many of those policies. Critics, however, point to an interview he gave in which he said some techniques (other than waterboarding) had saved lives. The Senate Intelligence Committee needs to satisfy itself — and the public — that he was not complicit in tactics that Obama has repudiated. Another focus should be targeted killings. The administration has made it clear that it intends to use drone strikes to target al-Qaida and other militants. But senators should press Brennan to expand on his public statements about how targeted killings are subjected to "rigorous standards and process of review." Too little is known about how those standards are applied to this troubling practice, and by whom.