Oyeniran v. Holder, 672 F.3d 800 (9th Cir. Mar. 6, 2012, amended May 3, 2012) (collateral estoppel applies in immigration proceedings; BIAs prior determination that alien had demonstrated he would be tortured upon his return to Nigeria was binding on the government in subsequent proceedings; BIA abused its discretion by denying motion to reopen on ground that alien knew of purported new evidence at time of the original ruling, where it was uncontroverted that alien lacked access to that evidence at that time, and the evidence was significant, dramatic, and compelling).