When a U.S. federal appeals court ruled last month that the CIA could no longer stay quiet about whether it has information on U.S. drone strikes, the decision made headlines around the world.

But for Jameel Jaffer, the Canadian-born lawyer who argued the case for the American Civil Liberties Union (ACLU), it was the end of a three-year saga and the culmination of hundreds of hours of work for the small legal team that took on the suit.

"We thought that the CIA's position was completely indefensible from the beginning, and it's gratifying finally to have an appeals court agree with us," Jaffer said by phone from New York City, where he lives. "But it's also a limited step towards transparency."

Since the first reported drone strike against al-Qaeda in 2002, which killed six people in Yemen including an American, the CIA has avoided officially acknowledging the program.

Such targeted killings have become more common in the intervening years, spawning a separate program operated by the U.S. military, and courting controversy along the way. Proponents argue that drone strikes are weakening al-Qaeda; critics say they create more militants than they kill and violate international law.

In Pakistan alone, more than 2,500 people have died in attacks by unmanned aircraft since 2004 – including more than 400 civilians, according one estimate by The Bureau of Investigative Journalism.

Gleaning information about the strikes has proven difficult, but the appeals court ruling could represent a small step toward coaxing the drone war out of the shadows.

The ACLU lawsuit centred on a Freedom of Information Act request, filed in 2010, seeking information on the conditions under which a person can be targeted by a drone strike, and on civilians who have been killed.

The CIA has yet to announce whether it will comply with the ruling or seek an appeal. If the decision stands, Jaffer is hopeful it will pave the way for a more serious debate in the U.S. "about how much of this secrecy is actually necessary and how much of it is just serving to protect officials from accountability of their decisions."

From Wall Street to Guantanamo

Since joining the ACLU more than a decade ago, Jaffer, 41, has emerged as a formidable critic of U.S. national security policy. For a while, his work took him regularly to Guantanamo Bay, Cuba, to monitor military tribunals there.

Another lawsuit he's involved with argues the CIA violated the U.S. Constitution when it carried out drone strikes in 2011 that killed three American citizens in Yemen, including an al-Qaeda leader named Anwar al-Awlaki and his 16-year-old son. Arguments in that case will be heard in July. If the ACLU is successful, Jaffer believes it could force the U.S. to significantly curtail its drone strikes.

But the path to his current position as deputy legal director with the New York-based rights group "wasn’t a straight line."

An MQ-1 Predator unmanned aircraft. (U.S. Air Force/Lt Col Leslie Pratt/Reuters)

Raised in Kingston, Ont., Jaffer moved to Toronto in grade 11 to attend Upper Canada College. After studying at a liberal arts school in the U.S., at the U.K.'s University of Cambridge and then Harvard Law School, he eventually wound up in a job working for a Wall Street law firm in equity derivatives.

He also started volunteering with the ACLU, visiting immigration detainees rounded up after the 9/11 attacks, and soon took a full-time job with the organization.

Working with those detainees "turned out to be a pretty affecting experience," he said.

Asked whether his years growing up north of the border have helped inform his work since then, Jaffer said it "keeps you aware that it's possible to do things differently."

But he also warns that countries including Canada should pay close attention to the policies being created in the United States to govern drone strikes.

"Even if you think there's no realistic chance that the U.S. will carry out targeted killings in Canada…when Iran or India or whatever country has the capability to carry out these targeted killings in the same way, they're going to be invoking the rules that the U.S. is creating right now."