Justices of the Supreme Court of the United States have heard oral arguments in a case challenging the federal government's right to monitor telephone and email conversations between people in the United States and those other countries.

The case, brought by lawyers, journalists and civil rights organizations, including Amnesty International, challenges a 2008 amendment to the Foreign Intelligence Surveillance Act that allows the eavesdropping to take place without a warrant.

They say the program violates the protection against illegal searches and seizures provided under the Fourth Amendment to the U.S. Constitution. They say that fear of surveillance forces people to adopt costly measures to ensure that communications abroad remain confidential.

But the arguments heard by the court focused not on the monitoring, but on whether the defendants have the right to bring their case before the courts.

The government argues that the defendants cannot show that they have personally suffered as a result of the wire-tapping.

Several justices questioned whether anyone would able to contest the law in court because the people targeted for wiretapping are not U.S. citizens and that the Americans being surveilled would never know that their conversations were being monitored.

The wire-tapping program was put into place by former President George W. Bush after the 2001 attacks on New York and Washington to find people with ties to al-Qaida and other terrorist groups. The program ended in 2007, but it was reinstated by Congress the following year.

The Supreme Court is expected to rule on the case next year.