Why did Justice Breyer think the Supreme Court should have returned McCutcheon v. Federal Election Commission for further evidence?

In his dissenting opinion for McCutcheon v. Federal Election Commission, Justice Stephen Breyer argued that the Supreme Court should have returned the case for further evidentiary proceedings because the Court’s expertise does not lie in "marshalling facts in the primary instance."1

Breyer contended that the plurality’s decision to simply reverse the district court’s ruling was premature. He believed that evidentiary proceedings were necessary to reliably determine whether the Court’s constitutional conclusions—specifically regarding the potential for circumvention of base contribution limits—were supported by empirical fact. By bypassing this process, he argued, the Court failed to properly evaluate whether the absence of aggregate limits would lead to the "grave problems of democratic legitimacy" that campaign finance laws were designed to address.1