Such arguments are known as amicus briefs, or “friend of the court” briefs, and are filed by third parties who wish to offer legal arguments that may be relevant in a case.  Federal trial judges rarely accept such briefs, which are typically filed not at the trial but at the appellate level.  But the denial is unusual for the ACLU, which for 94 years has entered civil liberties arguments in countless court proceedings.

In a similar setback for the defense, Tsarnaev’s attorneys continue to parry with prosecutors whom they say have been beyond stingy in the pre-trial discovery process. In their latest motion, defense attorneys say “the government continues to withhold reports and testimony of the greatest utility and interest concerning those closest to Tsarnaev.”