The Supreme Court threw out an attempt by U.S. citizens to challenge the expansion of a surveillance law used to monitor conversations of foreign spies and terrorist suspects, according to The Associated Press.

With a 5-4 vote, the court ruled that a group of American lawyers, journalists and organizations can’t sue to challenge the 2008 expansion of the Foreign Intelligence Surveillance Act (FISA) because they can’t prove that the government will monitor their conversations along with those of potential targets.

FISA was enacted in 1978 to allow the government to monitor conversations of foreign spies and terrorist suspects. The 2008 amendments allow the government to obtain from a secret court broad, yearlong intercept orders, AP reports.

Without proof that the law would directly affect them, Americans cannot sue, said the justices. They were reluctant to endorse standing theories that require guesswork, wrote Justice Samuel Alito, AP says.

Alito also says that the FISA expansion merely authorizes, but does not mandate or direct, the government monitoring. Respondents 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.”