US v. Blackstock: Blackstock was convicted in 1993 and filed a request seeking discovery from the Government in 2001. The district court, without notifying Blackstock, treated that filing as a petition under 28 USC 2255, because it mentioned that Blackstock's conviction was no longer valid under Apprendi. The district court denied the motion. In 2005, Blackstock filed a motion to set aside the district court's order, along with a 2255 petition. The district court denied both, holding that the 2255 petition was a "second or successive" petition and therefore prohibited under the AEDPA.
On appeal, the Fourth Circuit reversed, agreeing with Blackstock that the court's prior decision in US v. Emmanuel, 288 F.3d 644 (4th Cir. 2002), was not consistent with the Supreme Court's later decision in US v. Castro, 540 U.S. 375 (2003). Castro makes notice mandatory in cases like Blackstock's, whereas Emmanuel contained an exception to the notice rule that the district court had applied.