The Justice Department filed an appeal Friday to overturn a federal judge's ruling that the National Security Agency’s surveillance program is likely unconstitutional. 

President Obama, Attorney General Eric HolderEric H. HolderDOJ warrant of Trump resistance site triggers alarm Venture capital firm sues ex-Uber CEO for fraud Justice Dept. to meet with journalism group on subpoena guidelines MORE and NSA Director Keith Alexander formally appealed the Dec. 16 ruling made by U.S. District Court Judge Richard Leon.

Leon said the scope of the NSA’s operation to collect data on Americans’ phone calls is “almost Orwellian," comparing the program to George Orwell's book 1984.

The ruling was the first a court had made regarding the agency’s gathering of metadata from phone calls. Former NSA contractor Edward Snowden disclosed those operations in highly classified documents he leaked to journalists last year. 

In the case, Leon ordered the government to stop collecting data on calls from two plaintiffs, including conservative activist Larry Klayman. 

A New York District Court Judge, William Pauley, on the other hand, ruled in the last week of December that the NSA’s surveillance activities were legal.

The American Civil Liberties Union, which advocates for citizens’ privacy, formally appealed Pauley’s ruling on Thursday.

Similarly, Sen. Rand PaulRand PaulCurtis wins GOP primary for House seat vacated by Jason Chaffetz Glimmer of hope in bipartisan criminal justice reform effort Trump barrage stuns McConnell and his allies MORE (R-Ky.) has been pushing for months to lead a class action lawsuit against the NSA, charging that the surveillance program has violated people's Fourth Amendment rights. 

Paul's office confirmed to The Hill on Friday it will be filing the suit "soon." Breitbart News first reported the news.

The senator has been soliciting people on his website to sign up and join the lawsuit, and has encouraged phone and Internet providers to do the same.  

He told CNN in December it would be the first of its kind. 

“We have tens of thousands of people who have signed up for it,” Paul told CNN. “We're still exploring the legal aspect of whether we can file a class action suit. When you hear of class action suits, you hear of them mostly on liability. This would be a class action suit on a constitutional question, and it might be the first of its kind if we can file it.”