In its 2013 decision Clapper v. Amnesty International, the Supreme Court invoked separation of powers principles in holding that public interest groups alleging that the Government was spying on their foreign clients failed to demonstrate Article III standing because they could not prove that the future surveillance injury that they purportedly feared was “certainly impending.” Justice Breyer’s dissenting opinion argued “commonsense” suggested that the Government was spying on the plaintiffs’ foreign clients and proposed a “reasonable” or “high” probability standing test. Implicitly, the Clapper decision presented a third approach to standing decisions. In footnote 5, the majority opinion acknowledged that it had sometimes found standing based on a “substantial risk” standard that is arguably distinct from the “certainly impending” test. Justice Kennedy is the most likely supporter of a “substantial risk” standing test. Lower court decisions have divided in their interpretation of Clapper, but the Second and Federal Circuits have suggested that the substantial risk standard is applicable in some cases. The future of Article III standing depends on the three competing philosophies of standing in Clapper.