A bipartisan group of legislators looking to restore transparency to data collection programs conducted by the National Security Agency (NSA) won an initial victory late last week.

Passing 293-123, an amendment to H.R. 4870, the "Fiscal Year 2015 Department of Defense Appropriations Act," prohibits the agency from searching American citizens' communications without a warrant. A majority of both parties supported the NSA amendment.

The amendment was designed to stop so-called "back door searches."

As part of the 2008 FISA Amendments Act of 2008, the NSA was allowed to collect phone and e-mail data of noncitizens abroad without a warrant. According to a New York Times report, it also allowed for warrantless collection of citizens' data "if the Americans are communicating with or about a foreign target."

The primary cosponsors of the amendment included Republican U.S. Reps. Jim Sensenbrenner of Wisconsin and Thomas Massie of Kentucky as well as Democrats Zoe Lofgren of California and Rush Holt of New Jersey. A joint statement from the cosponsors said:

"By adopting this amendment, Congress can take a sure step toward shutting the back door on mass surveillance. . . . Congress has an ongoing obligation to conduct oversight of the intelligence community and its surveillance authorities."

Similar movements to restrict the NSA's data collection authority, such as the so-called Amash Amendment in 2013, have been publicized and ultimately defeated. Massie said the swiftness of the vote played into its proponents' favor:

"It was to our benefit that it moved quickly without a lot of advance notice, because  didn't have time to mount a disinformation campaign."

Some privacy advocates, such as California U.S. Rep. Adam Schiff voted against the amendment, in part because of issues with its language. Lofgren admitted the amendment is not perfect, but that it was a necessary step forward:

"There's a lot of information about US people outside the United States - for example, server farms are outside the US and have all the information about Americans  the NSA has admitted publicly that they do in fact collect information about Americans without a warrant using this process  they have admitted they query the database for Americans without a warrant."

The passage of the amendment is significant because it works to restore language stripped from the USA Freedom Act, which passed the House in May. The original bill sought to drastically reform data collection, but language revisions cost it the public support of tech companies such as Google and Facebook.

The bill and all of its amendments now move to the U.S. Senate where passage is likely to be more difficult.