It must be true...

...it was cited in an amicus. That appears now to be the moral equivalent of, "It's a fact. I read it on the Internet."

Evidently, justices of the US Supreme Court have, on at least several occasions, buttressed their opinions with assertions passed off as facts in friend-of-the-court briefings. The problem is, no one seems to know where the supposed "facts" come from.

A few examples:

In a 2011 decision about the privacy rights of scientists who worked on government space programs, Justice Alito cited an amicus brief to show that more than 88 percent of American companies perform background checks on their workers.

“Where this number comes from is a mystery,” Professor Larsen wrote. “It is asserted in the brief without citation.”

In a 2012 decision allowing strip searches of people arrested for even minor offenses as they are admitted to jail, Justice Anthony M. Kennedy cited an amicus brief to show that there are “an increasing number of gang members” entering the nation’s prisons and jails. The brief itself did little more than assert that “there is no doubt” this was so.

And in 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.

Read the whole thing.