From a decision by Magistrate Judge Zia Faruqui (D.D.C.) in In re: Search of One Device and Two Individuals (decided last month but just released Tuesday):
The videos [of the arrest] showed the defendant and [Redacted] on top of each other, falling down the stairs while being tackled by police officers. While they all were tumbling down, a gun fell from their area. Defendant's [Redacted] exclaimed right away that the gun was [Redacted]. The gun was in fact registered to [Redacted] and [Redacted] had a license to carry it.
The defendant was prosecuted on the theory that he was the one possessing the gun, which would be a crime because the defendant (but not the man he was fighting, whose gun this was) was a felon. Among other things, the court rejected the request for a warrant to search