A new report from The New York Times indicates that Supreme Court justices regularly incorporate data into their decisions that has no real factual backing. The justices use amicus briefs — ostensibly helpful but often ideologically motivated statements submitted by interested parties — when deciding cases, and those briefs are often not to be trusted:
Some of the factual assertions in recent amicus briefs would not pass muster in a high school research paper. But that has not stopped the Supreme Court from relying on them. Recent opinions have cited "facts" from amicus briefs that were backed up by blog posts, emails or nothing at all. [The New York Times]
[I]n a 2013 decision, Justice Stephen G. Breyer cited an amicus brief to establish that American libraries hold 200 million books that were published abroad, a point of some significance in the copyright dispute before the court. The figure in the brief came from a blog post. The blog has been discontinued. [The New York Times]
As law professor Allison Orr Larsen of the College of William and Mary comments, this "really makes you wonder how much digging the justices are doing."