Vasquez-Ramirez v. US Dist. Court for the S. Dist. of California, 443 F.3d 692 (9th Cir. Apr. 6, 2006) (once a prosecutor brings charges against a defendant, Federal Rule of Criminal Procedure 11 requires judge to accept defendants guilty plea to those charges, regardless of whether the judge feels prosecutors charging decision was too aggressive or too lenient).
http://caselaw.lp.findlaw.com/data2/circs/9th/0475715p.pdf