Nath v. Gonzales, ___ F.3d ___, 2006 WL 3110424 (9th Cir. Nov. 3, 2006) (government has burden of proof by clear and convincing evidence that order vacating conviction was ineffective to eliminate conviction for immigration purposes when respondent made motion to reopen removal proceedings after conviction had been vacated; because order was ambiguous as to whether it had been based on a ground of invalidity, government could not meet its burden of proof, and BIA abused its discretion in denying motion to reopen).