What is the test for a criminal defendant to succeed on a claim of inadequate legal assistance?

Every criminal defendant is entitled to constitutionally adequate legal assistance. (People v. Frye (1998) 18 Cal.4th 894, 979.) To succeed on a claim of inadequate assistance, a defendant must show first that "counsel's representation was 'deficient' in that it 'fell below an objective standard of reasonableness.... [] ... under prevailing professional norms.'" (Ibid.) This review of counsel's performance is deferential. (In re Jones (1996) 13 Cal.4th 552, 561.) There is thus "a 'strong presumption that counsel's conduct falls within the wide range of reasonable professional assistance' [citations], and we accord great deference to counsel's tactical decisions. [Citation.] Were it otherwise, appellate courts would be required to engage in the '"perilous process"' of second-guessing counsel's trial strategy. [Citation.]" (People v. Frye, supra, at pp. 979-980, fn. omitted.)

"A fair assessment of attorney performance requires that every effort be made to eliminate the distorting effects of hindsight, to reconstruct the circumstances of counsel's challenged conduct, and to evaluate the conduct from counsel's perspective at the time. Because of difficulties inherent in making the evaluation, ... the defendant must overcome the presumption that, under the circumstances, the challenged action 'might be considered sound trial strategy.' [Citation]." (Strickland v. Washington (1984) 466 U.S. 668 at p. 689; see also In re Jones, supra, 13 Cal.4th at p. 561.)