From the Huffington Post:
Speaking from his home in the San Francisco Bay Area, Ellsberg, 82, told HuffPost Live hosts Ahmed Shihab-Eldin and Josh Zepps that he, Snowden and accused WikiLeaks leaker Pfc. Bradley Manning "chose to give priority to our oath to defend and support the Constitution, rather than our promise to keep secrets for our boss or for our agency, when those secrets were concealing evidence that the Constitution was being violated."
...Ellsberg, who faced 12 felony counts for leaking the Pentagon Papers -- charges which were ultimately dropped -- said that Snowden "made the right choice." Ellsberg called PRISM, the program that allegedly collects user data from large technology companies like Google, Yahoo! and Facebook, as well as the NSA's broad collection of American's telephone records, "clearly unconstitutional."