What is the test for determining whether a defendant is competent to stand trial?

Before holding the competency hearing, "the court may order that a psychiatric or psychological examination of the defendant be conducted." Id. 4241(b). At the hearing, the defendant "shall be represented by counsel" and "shall be afforded an opportunity to testify, to present evidence, to subpoena witnesses on his behalf, and to confront and cross-examine witnesses who appear at the hearing." Id. 4247(d). District courts have an independent and continuing obligation to ensure a defendant's competency. See United States v. Kerr, 752 F.3d 206, 215-16 (2d Cir. 2014). We review a district court's determination of whether there is reasonable cause to question the defendant's competency pursuant to 18 U.S.C. 4241(a) for abuse of discretion. United States v. Arenburg, 605 F.3d 164, 169 (2d Cir. 2010) (per curiam) (citing Quintieri, 306 F.3d at 1232-33).