THE CHIEF of the independent government agency tasked with evaluating the risk that federal counterterrorism programs present to Americans’ constitutional rights is stepping down unexpectedly.

David Medine, who was confirmed as chairman of the Privacy and Civil Liberties Oversight Board shortly before NSA whistleblower Edward Snowden revealed the massive scale of the U.S. government’s spying operations, has been tugging on the reins of expanding government surveillance power since.

The board is often referred to by its acronym, PCLOB, pronounced “pee-clawb.”

Medine was scheduled to stay on until January 2018. His last day will now be July 1.

“During my tenure and thanks to the support of the president and Congress, the board has been able to carry out its timely mission of conducting oversight and providing advice to ensure that federal counterterrorism efforts properly balance national security with privacy and civil liberties,” Medine said in a statement about his resignation on Tuesday.

Medine wrote that he has decided to work to protect low-income consumers and the privacy of their data in developing countries, but he did not name the organization he’ll be joining.

Prior to joining the board, Medine worked on similar issues — privacy and data security — both in government, including at the Federal Trade Commission, and private practice. He could not be reached for comment Tuesday morning.

President Barack Obama thanked him in an emailed statement, but gave no indication of when he might nominate a replacement or who it might be. “David has served our nation as PCLOB chairman during an especially momentous period, coinciding with a concerted examination of our national security tools and policies to ensure they are consistent with my administration’s commitment to civil liberties and individual privacy,” Obama wrote.

The Privacy and Civil Liberties Oversight Board, first created in 2004 after counterterrorism efforts ramped up in response to the 9/11 attacks, was shuttered and reborn as an independent watchdog in 2013.

The bipartisan five-member panel — chosen by the president and confirmed by the Senate — had access to many of the classified details that surveillance reformers have been clamoring for since Snowden, and its reports have become central to the ongoing debate.

In 2014, the board criticized the NSA’s mass surveillance program vacuuming up millions of Americans’ telephone records, supposedly authorized under Section 215 of the USA Patriot Act —  concluding that there was no real legal foundation for it and it wasn’t fighting terrorism anyway.

Congress chose to shutter the program in 2015, replacing it with a new one that keeps the phone records in the hands of the telephone companies, not on the NSA’s servers.

But PCLOB’s review of the NSA’s overseas spying frustrated privacy and civil liberties activists. The board’s review of the NSA’s surveillance program under Section 702 of the Foreign Intelligence Surveillance Act left unanswered many central questions, including: How much American data is swept up in a program ostensibly intended to capture only foreign communications?

And the board is only now working on a report on the most massive body of spying: NSA surveillance conducted under the Reagan-era Executive Order 12333. Medine’s departure “will not affect the 12333 report,” writes PCLOB spokesperson Jen Burita in an email to The Intercept. “The board is still going to release it this year.”

Top Photo: David Medine, chairman of the Privacy and Civil Liberties Oversight Board.