The Supreme Court split along ideological lines Tuesday in dismissing a challenge to an expanded federal law that allows the interception of electronic communications between foreign targets and people in the United States.

Justice Samuel A. Alito Jr. wrote for the conservative majority in saying that the lawyers, journalists and human rights organizations that brought the suit cannot prove they have been caught up in the surveillance and thus may not challenge the law’s 2008 expansion.

The 5 to 4 ruling did not touch on the constitutionality of the law, and challengers said it will be almost impossible now to get that issue before a court.

The amendments, passed to bolster national security in the wake of terrorism threats, carry “far-reaching implications for Americans’ privacy,” said Jameel Jaffer, deputy legal director of the American Civil Liberties Union, one of the groups that sued.

“This ruling insulates the statute from meaningful judicial review and leaves Americans’ privacy rights to the mercy of the political branches.”

After the Sept. 11 attacks, President George W. Bush authorized the National Security Agency to conduct warrantless wiretapping of telephone and e-mail communications in which one party was outside the U.S. and was “reasonably believed to be a member or agent of al Qaeda” or other terrorist organization.

When the program came to light, the administration asked Congress to amend the Foreign Intelligence Surveillance Act to include broader powers. It allows national security officials to obtain authorization from the Foreign Intelligence Surveillance Court to track suspects for up to one year.

The requests are almost never denied. In 2011, all but two of the 1,676 were approved, and those two were withdrawn by the government.

Lawyers, journalists and human rights groups challenged the 2008 amendments on the day they took effect. They said some of the people they represent or those with whom they exchange information are likely targets of the surveillance, and thus their communications were being monitored as well.

A panel of the U.S. Court of Appeals for the 2nd Circuit said that was enough for the lawsuit to proceed. But the Supreme Court majority Tuesday said it was not.

Because information about targets is secret, there is no way for challengers to prove they are caught up in the surveillance, Alito wrote, so they have no legal grounds to challenge the law.

“Simply put, [the challengers] can only speculate as to how the attorney general and the director of national intelligence will exercise their discretion in determining which communications to target,” Alito wrote.

In addition, he said it was not enough that the individuals had taken precautions to protect the confidentiality of their communications, such as visiting their contacts rather than relying on phone calls or e-mails, Alito said. Otherwise, he said, it would be enough to get into court “simply by making an expenditure based on a nonparanoid fear.”

He was joined by Chief Justice John G. Roberts Jr. and Justices Antonin Scalia, Anthony M. Kennedy and Clarence Thomas.

Justice Stephen G. Breyer said the majority was ignoring precedent — and the obvious.

He said the challengers’ fears were not speculative, but common sense.

“We need only assume that the government is doing its job (to find out about, and combat, terrorism) in order to conclude that there is a high probability that the government will intercept at least some electronic communication to which at least some of the plaintiffs are parties,” Breyer wrote.

He said the court had found standing for parties in the past in which injury was “far less certain than here.”

He was joined by Justices Ruth Bader Ginsburg, Sonia Sotomayor and Elena Kagan.

The case is Clapper v. Amnesty International, USA .

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