Leon granted an injunction that would have stopped national security officials from collecting telephone record data on two of the plaintiffs. (The challengers have not certified a class to date.) However, the judge put that order on hold pending the government’s likely appeal.

Describing the government's surveillance efforts as "almost-Orwellian," U.S. District Judge Richard Leon found the challengers in a lawsuit in Washington were likely to succeed on their Fourth Amendment privacy claims.

The National Security Agency's bulk collection of telephone records likely violates privacy rights of individual Americans, a federal trial judge in Washington ruled today.

The judge said he had "serious doubts" about the effectiveness of the telephone record collection program in aiding time-sensitive terrorism investigations. As a result, he said, the plaintiffs showed their privacy interests likely outweighed the government's stated interests in gathering the data.

"Indeed, I have little doubt that the author of our Constitution, James Madison, who cautioned us to beware 'the abridgement of freedom of the people by gradual and silent encroachments by those in power,' would be aghast," Leon wrote.

Attorney and activist Larry Klayman filed several lawsuits challenging government surveillance efforts following leaks earlier this year by ex-National Security Agency contractor Edward Snowden. Klayman and his co-plaintiffs sued as subscribers of telecommunications companies that were reportedly the subject of NSA intelligence-gathering efforts.

The plaintiffs accused the government of violating their constitutional rights and exceeding its authority under the Administrative Procedure Act. Leon found the court lacked standing to consider the APA claim, but could consider the constitutional claims.

The Foreign Intelligence Surveillance Court reviews warrants for government surveillance, but Leon said that didn't stop him from having jurisdiction to hear constitutional claims related to that surveillance.

"While Congress has great latitude to create statutory schemes like [the Foreign Intelligence Surveillance Act], it may not hang a cloak of secrecy over the Constitution," Leon wrote.

Although the plaintiffs brought a number of constitutional claims involving the collection of phone record metadata, Leon said they were most likely to succeed on a Fourth Amendment claim.

For more than seven years, Leon noted, the government had collected telephone records that revealed information on what phone numbers made and received calls, when the calls took place and how long the calls lasted. The government said the metadata records were used to identify connections to terrorists and didn’t include information on who made the calls or what they discussed.

Leon dismissed the government’s argument the 1979 Supreme Court case Smith v. Maryland—which involved the warrantless use of a “pen register”—permitted the bulk collection of telephone metadata. (The authorities use pen registers to record the numbers a person dials.)

“When do present-day circumstances—the evolution of the government’s surveillance capabilities, citizens’ phone habits, and the relationship between the NSA and telecom companies—become so thoroughly unlike those considered by the Supreme Court thirty-four years ago that a precedent like Smith does not apply?” Leon wrote. “The answer, unfortunately for the government, is now.”

The judge said he was “convinced that the surveillance program now before me is so different from a simple pen register that Smith is of little value in assessing whether the Bulk Telephony Metadata Program constitutes a Fourth Amendment search.”

“To the contrary,” Leon wrote, “I believe that the bulk telephony metadata collection and analysis almost certainly does violate a reasonable expectation of privacy.”

Leon said “the almost-Orwellian technology that enables the government to store and analyze the phone metadata of every telephone user in the United States is unlike anything that could have been conceived in 1979.”

The judge added that the amount of information contained in phone records today was greater as well. He said he could no longer use "as my North Star a case that predates the rise of cell phones."

Although Leon granted the injunction, he stayed that order pending the government's appeal "in light of the significant national security interests at stake in this case and the novelty of the constitutional issues."

Klayman could not immediately be reached for comment. A spokesman for the U.S. Department of Justice, Andrew Ames, said the government is reviewing the court's decision.

"We believe the program is constitutional as previous judges have found," he said. "We have no further comment at this time.”

U.S. Senate Judiciary Committee Chairman Patrick Leahy (D) said in a statement today that in light of Leon's ruling, "it is clear to me that even more oversight is needed in the future."

"Americans deserve an open and transparent debate about the constitutionality, efficacy, and appropriateness of the government’s dragnet collection programs," Leahy said. "I welcome today’s district court ruling regarding the collection of phone metadata, particularly because the litigants were afforded the opportunity to participate in an adversarial process."

Updated at 3:59 p.m. Mike Scarcella contributed to this report. National Law Journal photo by Diego M. Radzinschi.